diff --git a/app/eth2wrap/eth2wrap.go b/app/eth2wrap/eth2wrap.go
index 00f4eabc5..5dda9a396 100644
--- a/app/eth2wrap/eth2wrap.go
+++ b/app/eth2wrap/eth2wrap.go
@@ -101,7 +101,7 @@ func NewMultiHTTP(timeout time.Duration, addresses ...string) (Client, error) {
 func newMulti(clients []Client) Client {
 	return multi{
 		clients:  clients,
-		selector: newBestSelector(len(clients), bestPeriod),
+		selector: newBestSelector(bestPeriod),
 	}
 }
 
@@ -114,17 +114,17 @@ type multi struct {
 	selector *bestSelector
 }
 
-// bestIdx increments the selector with the best client index.
-func (m multi) bestIdx(i int) {
-	m.selector.Increment(i)
-}
-
 func (multi) Name() string {
 	return "eth2wrap.multi"
 }
 
 func (m multi) Address() string {
-	return m.clients[m.selector.Best()].Address()
+	address, ok := m.selector.BestAddress()
+	if !ok {
+		return m.clients[0].Address()
+	}
+
+	return address
 }
 
 func (m multi) SetValidatorCache(valCache func(context.Context) (ActiveValidators, error)) {
@@ -159,7 +159,7 @@ func (m multi) ProposerConfig(ctx context.Context) (*eth2exp.ProposerConfigRespo
 		func(ctx context.Context, cl Client) (*eth2exp.ProposerConfigResponse, error) {
 			return cl.ProposerConfig(ctx)
 		},
-		nil, m.bestIdx,
+		nil, m.selector,
 	)
 	if err != nil {
 		incError(label)
@@ -177,7 +177,7 @@ func (m multi) AggregateBeaconCommitteeSelections(ctx context.Context, selection
 		func(ctx context.Context, cl Client) ([]*eth2exp.BeaconCommitteeSelection, error) {
 			return cl.AggregateBeaconCommitteeSelections(ctx, selections)
 		},
-		nil, m.bestIdx,
+		nil, m.selector,
 	)
 	if err != nil {
 		incError(label)
@@ -195,7 +195,7 @@ func (m multi) AggregateSyncCommitteeSelections(ctx context.Context, selections
 		func(ctx context.Context, cl Client) ([]*eth2exp.SyncCommitteeSelection, error) {
 			return cl.AggregateSyncCommitteeSelections(ctx, selections)
 		},
-		nil, m.bestIdx,
+		nil, m.selector,
 	)
 	if err != nil {
 		incError(label)
@@ -213,7 +213,7 @@ func (m multi) BlockAttestations(ctx context.Context, stateID string) ([]*eth2p0
 		func(ctx context.Context, cl Client) ([]*eth2p0.Attestation, error) {
 			return cl.BlockAttestations(ctx, stateID)
 		},
-		nil, m.bestIdx,
+		nil, m.selector,
 	)
 	if err != nil {
 		incError(label)
@@ -231,7 +231,7 @@ func (m multi) NodePeerCount(ctx context.Context) (int, error) {
 		func(ctx context.Context, cl Client) (int, error) {
 			return cl.NodePeerCount(ctx)
 		},
-		nil, m.bestIdx,
+		nil, m.selector,
 	)
 	if err != nil {
 		incError(label)
@@ -245,14 +245,11 @@ func (m multi) NodePeerCount(ctx context.Context) (int, error) {
 // first successful result or first error.
 // The bestIdxFunc is called with the index of the client returning a successful response.
 func provide[O any](ctx context.Context, clients []Client,
-	work forkjoin.Work[Client, O], isSuccessFunc func(O) bool, bestIdxFunc func(int),
+	work forkjoin.Work[Client, O], isSuccessFunc func(O) bool, bestSelector *bestSelector,
 ) (O, error) {
 	if isSuccessFunc == nil {
 		isSuccessFunc = func(O) bool { return true }
 	}
-	if bestIdxFunc == nil {
-		bestIdxFunc = func(int) {}
-	}
 
 	fork, join, cancel := forkjoin.New(ctx, work,
 		forkjoin.WithoutFailFast(),
@@ -272,11 +269,8 @@ func provide[O any](ctx context.Context, clients []Client,
 		if ctx.Err() != nil {
 			return zero, ctx.Err()
 		} else if res.Err == nil && isSuccessFunc(res.Output) {
-			// TODO(corver): Find a better way to get the index of successful client.
-			for i, client := range clients {
-				if client.Address() == res.Input.Address() {
-					bestIdxFunc(i)
-				}
+			if bestSelector != nil {
+				bestSelector.Increment(res.Input.Address())
 			}
 
 			return res.Output, nil
@@ -298,14 +292,12 @@ func provide[O any](ctx context.Context, clients []Client,
 type empty struct{}
 
 // submit proxies provide, but returns nil instead of a successful result.
-func submit(ctx context.Context, clients []Client, work func(context.Context, Client) error,
-	bestIdxFunc func(int),
-) error {
+func submit(ctx context.Context, clients []Client, work func(context.Context, Client) error, selector *bestSelector) error {
 	_, err := provide(ctx, clients,
 		func(ctx context.Context, cl Client) (empty, error) {
 			return empty{}, work(ctx, cl)
 		},
-		nil, bestIdxFunc,
+		nil, selector,
 	)
 
 	return err
@@ -368,52 +360,48 @@ func wrapError(ctx context.Context, err error, label string, fields ...z.Field)
 }
 
 // newBestSelector returns a new bestSelector.
-func newBestSelector(n int, period time.Duration) *bestSelector {
+func newBestSelector(period time.Duration) *bestSelector {
 	return &bestSelector{
-		n:      n,
+		counts: make(map[string]int),
+		start:  time.Now(),
 		period: period,
-		counts: make([]int, n),
 	}
 }
 
 // bestSelector calculates the "best client index" per period.
 type bestSelector struct {
-	n      int
-	mu     sync.Mutex
+	mu     sync.RWMutex
+	counts map[string]int
 	start  time.Time
 	period time.Duration
-	counts []int
 }
 
-// Best returns the best index or 0 if no counts.
-func (s *bestSelector) Best() int {
-	s.mu.Lock()
-	defer s.mu.Unlock()
-
-	var resp, count int
-	for i, c := range s.counts {
-		if c > count {
-			resp = i
-			count = c
+// BestAddress returns the best client address when ok is true.
+func (s *bestSelector) BestAddress() (address string, ok bool) {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+
+	var maxCount int
+	for addr, count := range s.counts {
+		if count > maxCount {
+			ok = true
+			address = addr
+			maxCount = count
 		}
 	}
 
-	return resp
+	return address, ok
 }
 
-// Increment increments the counter for the given index.
-func (s *bestSelector) Increment(i int) {
+// Increment increments the counter for the given address.
+func (s *bestSelector) Increment(address string) {
 	s.mu.Lock()
 	defer s.mu.Unlock()
 
-	if i < 0 || i >= s.n {
-		panic("invalid index") // This should never happen
-	}
-
 	if time.Since(s.start) > s.period { // Reset counters after period.
-		s.counts = make([]int, s.n)
+		s.counts = make(map[string]int)
 		s.start = time.Now()
 	}
 
-	s.counts[i]++
+	s.counts[address]++
 }
diff --git a/app/eth2wrap/eth2wrap_gen.go b/app/eth2wrap/eth2wrap_gen.go
index c98044151..1aae71c95 100644
--- a/app/eth2wrap/eth2wrap_gen.go
+++ b/app/eth2wrap/eth2wrap_gen.go
@@ -75,7 +75,7 @@ func (m multi) SlotDuration(ctx context.Context) (time.Duration, error) {
 		func(ctx context.Context, cl Client) (time.Duration, error) {
 			return cl.SlotDuration(ctx)
 		},
-		nil, m.bestIdx,
+		nil, m.selector,
 	)
 
 	if err != nil {
@@ -97,7 +97,7 @@ func (m multi) SlotsPerEpoch(ctx context.Context) (uint64, error) {
 		func(ctx context.Context, cl Client) (uint64, error) {
 			return cl.SlotsPerEpoch(ctx)
 		},
-		nil, m.bestIdx,
+		nil, m.selector,
 	)
 
 	if err != nil {
@@ -117,7 +117,7 @@ func (m multi) SignedBeaconBlock(ctx context.Context, opts *api.SignedBeaconBloc
 		func(ctx context.Context, cl Client) (*api.Response[*spec.VersionedSignedBeaconBlock], error) {
 			return cl.SignedBeaconBlock(ctx, opts)
 		},
-		nil, m.bestIdx,
+		nil, m.selector,
 	)
 
 	if err != nil {
@@ -137,7 +137,7 @@ func (m multi) AggregateAttestation(ctx context.Context, opts *api.AggregateAtte
 		func(ctx context.Context, cl Client) (*api.Response[*phase0.Attestation], error) {
 			return cl.AggregateAttestation(ctx, opts)
 		},
-		isAggregateAttestationOk, m.bestIdx,
+		isAggregateAttestationOk, m.selector,
 	)
 
 	if err != nil {
@@ -157,7 +157,7 @@ func (m multi) SubmitAggregateAttestations(ctx context.Context, aggregateAndProo
 		func(ctx context.Context, cl Client) error {
 			return cl.SubmitAggregateAttestations(ctx, aggregateAndProofs)
 		},
-		m.bestIdx,
+		m.selector,
 	)
 
 	if err != nil {
@@ -177,7 +177,7 @@ func (m multi) AttestationData(ctx context.Context, opts *api.AttestationDataOpt
 		func(ctx context.Context, cl Client) (*api.Response[*phase0.AttestationData], error) {
 			return cl.AttestationData(ctx, opts)
 		},
-		nil, m.bestIdx,
+		nil, m.selector,
 	)
 
 	if err != nil {
@@ -197,7 +197,7 @@ func (m multi) SubmitAttestations(ctx context.Context, attestations []*phase0.At
 		func(ctx context.Context, cl Client) error {
 			return cl.SubmitAttestations(ctx, attestations)
 		},
-		m.bestIdx,
+		m.selector,
 	)
 
 	if err != nil {
@@ -217,7 +217,7 @@ func (m multi) AttesterDuties(ctx context.Context, opts *api.AttesterDutiesOpts)
 		func(ctx context.Context, cl Client) (*api.Response[[]*apiv1.AttesterDuty], error) {
 			return cl.AttesterDuties(ctx, opts)
 		},
-		nil, m.bestIdx,
+		nil, m.selector,
 	)
 
 	if err != nil {
@@ -237,7 +237,7 @@ func (m multi) DepositContract(ctx context.Context, opts *api.DepositContractOpt
 		func(ctx context.Context, cl Client) (*api.Response[*apiv1.DepositContract], error) {
 			return cl.DepositContract(ctx, opts)
 		},
-		nil, m.bestIdx,
+		nil, m.selector,
 	)
 
 	if err != nil {
@@ -258,7 +258,7 @@ func (m multi) SyncCommitteeDuties(ctx context.Context, opts *api.SyncCommitteeD
 		func(ctx context.Context, cl Client) (*api.Response[[]*apiv1.SyncCommitteeDuty], error) {
 			return cl.SyncCommitteeDuties(ctx, opts)
 		},
-		nil, m.bestIdx,
+		nil, m.selector,
 	)
 
 	if err != nil {
@@ -278,7 +278,7 @@ func (m multi) SubmitSyncCommitteeMessages(ctx context.Context, messages []*alta
 		func(ctx context.Context, cl Client) error {
 			return cl.SubmitSyncCommitteeMessages(ctx, messages)
 		},
-		m.bestIdx,
+		m.selector,
 	)
 
 	if err != nil {
@@ -298,7 +298,7 @@ func (m multi) SubmitSyncCommitteeSubscriptions(ctx context.Context, subscriptio
 		func(ctx context.Context, cl Client) error {
 			return cl.SubmitSyncCommitteeSubscriptions(ctx, subscriptions)
 		},
-		m.bestIdx,
+		m.selector,
 	)
 
 	if err != nil {
@@ -318,7 +318,7 @@ func (m multi) SyncCommitteeContribution(ctx context.Context, opts *api.SyncComm
 		func(ctx context.Context, cl Client) (*api.Response[*altair.SyncCommitteeContribution], error) {
 			return cl.SyncCommitteeContribution(ctx, opts)
 		},
-		nil, m.bestIdx,
+		nil, m.selector,
 	)
 
 	if err != nil {
@@ -338,7 +338,7 @@ func (m multi) SubmitSyncCommitteeContributions(ctx context.Context, contributio
 		func(ctx context.Context, cl Client) error {
 			return cl.SubmitSyncCommitteeContributions(ctx, contributionAndProofs)
 		},
-		m.bestIdx,
+		m.selector,
 	)
 
 	if err != nil {
@@ -358,7 +358,7 @@ func (m multi) Proposal(ctx context.Context, opts *api.ProposalOpts) (*api.Respo
 		func(ctx context.Context, cl Client) (*api.Response[*api.VersionedProposal], error) {
 			return cl.Proposal(ctx, opts)
 		},
-		nil, m.bestIdx,
+		nil, m.selector,
 	)
 
 	if err != nil {
@@ -378,7 +378,7 @@ func (m multi) BeaconBlockRoot(ctx context.Context, opts *api.BeaconBlockRootOpt
 		func(ctx context.Context, cl Client) (*api.Response[*phase0.Root], error) {
 			return cl.BeaconBlockRoot(ctx, opts)
 		},
-		nil, m.bestIdx,
+		nil, m.selector,
 	)
 
 	if err != nil {
@@ -398,7 +398,7 @@ func (m multi) SubmitProposal(ctx context.Context, block *api.VersionedSignedPro
 		func(ctx context.Context, cl Client) error {
 			return cl.SubmitProposal(ctx, block)
 		},
-		m.bestIdx,
+		m.selector,
 	)
 
 	if err != nil {
@@ -418,7 +418,7 @@ func (m multi) SubmitBeaconCommitteeSubscriptions(ctx context.Context, subscript
 		func(ctx context.Context, cl Client) error {
 			return cl.SubmitBeaconCommitteeSubscriptions(ctx, subscriptions)
 		},
-		m.bestIdx,
+		m.selector,
 	)
 
 	if err != nil {
@@ -438,7 +438,7 @@ func (m multi) BlindedProposal(ctx context.Context, opts *api.BlindedProposalOpt
 		func(ctx context.Context, cl Client) (*api.Response[*api.VersionedBlindedProposal], error) {
 			return cl.BlindedProposal(ctx, opts)
 		},
-		nil, m.bestIdx,
+		nil, m.selector,
 	)
 
 	if err != nil {
@@ -458,7 +458,7 @@ func (m multi) SubmitBlindedProposal(ctx context.Context, block *api.VersionedSi
 		func(ctx context.Context, cl Client) error {
 			return cl.SubmitBlindedProposal(ctx, block)
 		},
-		m.bestIdx,
+		m.selector,
 	)
 
 	if err != nil {
@@ -478,7 +478,7 @@ func (m multi) SubmitValidatorRegistrations(ctx context.Context, registrations [
 		func(ctx context.Context, cl Client) error {
 			return cl.SubmitValidatorRegistrations(ctx, registrations)
 		},
-		m.bestIdx,
+		m.selector,
 	)
 
 	if err != nil {
@@ -498,7 +498,7 @@ func (m multi) Fork(ctx context.Context, opts *api.ForkOpts) (*api.Response[*pha
 		func(ctx context.Context, cl Client) (*api.Response[*phase0.Fork], error) {
 			return cl.Fork(ctx, opts)
 		},
-		nil, m.bestIdx,
+		nil, m.selector,
 	)
 
 	if err != nil {
@@ -518,7 +518,7 @@ func (m multi) ForkSchedule(ctx context.Context, opts *api.ForkScheduleOpts) (*a
 		func(ctx context.Context, cl Client) (*api.Response[[]*phase0.Fork], error) {
 			return cl.ForkSchedule(ctx, opts)
 		},
-		nil, m.bestIdx,
+		nil, m.selector,
 	)
 
 	if err != nil {
@@ -538,7 +538,7 @@ func (m multi) Genesis(ctx context.Context, opts *api.GenesisOpts) (*api.Respons
 		func(ctx context.Context, cl Client) (*api.Response[*apiv1.Genesis], error) {
 			return cl.Genesis(ctx, opts)
 		},
-		nil, m.bestIdx,
+		nil, m.selector,
 	)
 
 	if err != nil {
@@ -558,7 +558,7 @@ func (m multi) NodeSyncing(ctx context.Context, opts *api.NodeSyncingOpts) (*api
 		func(ctx context.Context, cl Client) (*api.Response[*apiv1.SyncState], error) {
 			return cl.NodeSyncing(ctx, opts)
 		},
-		isSyncStateOk, m.bestIdx,
+		isSyncStateOk, m.selector,
 	)
 
 	if err != nil {
@@ -578,7 +578,7 @@ func (m multi) NodeVersion(ctx context.Context, opts *api.NodeVersionOpts) (*api
 		func(ctx context.Context, cl Client) (*api.Response[string], error) {
 			return cl.NodeVersion(ctx, opts)
 		},
-		nil, m.bestIdx,
+		nil, m.selector,
 	)
 
 	if err != nil {
@@ -599,7 +599,7 @@ func (m multi) SubmitProposalPreparations(ctx context.Context, preparations []*a
 		func(ctx context.Context, cl Client) error {
 			return cl.SubmitProposalPreparations(ctx, preparations)
 		},
-		m.bestIdx,
+		m.selector,
 	)
 
 	if err != nil {
@@ -619,7 +619,7 @@ func (m multi) ProposerDuties(ctx context.Context, opts *api.ProposerDutiesOpts)
 		func(ctx context.Context, cl Client) (*api.Response[[]*apiv1.ProposerDuty], error) {
 			return cl.ProposerDuties(ctx, opts)
 		},
-		nil, m.bestIdx,
+		nil, m.selector,
 	)
 
 	if err != nil {
@@ -639,7 +639,7 @@ func (m multi) Spec(ctx context.Context, opts *api.SpecOpts) (*api.Response[map[
 		func(ctx context.Context, cl Client) (*api.Response[map[string]any], error) {
 			return cl.Spec(ctx, opts)
 		},
-		nil, m.bestIdx,
+		nil, m.selector,
 	)
 
 	if err != nil {
@@ -659,7 +659,7 @@ func (m multi) Validators(ctx context.Context, opts *api.ValidatorsOpts) (*api.R
 		func(ctx context.Context, cl Client) (*api.Response[map[phase0.ValidatorIndex]*apiv1.Validator], error) {
 			return cl.Validators(ctx, opts)
 		},
-		nil, m.bestIdx,
+		nil, m.selector,
 	)
 
 	if err != nil {
@@ -679,7 +679,7 @@ func (m multi) SubmitVoluntaryExit(ctx context.Context, voluntaryExit *phase0.Si
 		func(ctx context.Context, cl Client) error {
 			return cl.SubmitVoluntaryExit(ctx, voluntaryExit)
 		},
-		m.bestIdx,
+		m.selector,
 	)
 
 	if err != nil {
@@ -699,7 +699,7 @@ func (m multi) Domain(ctx context.Context, domainType phase0.DomainType, epoch p
 		func(ctx context.Context, cl Client) (phase0.Domain, error) {
 			return cl.Domain(ctx, domainType, epoch)
 		},
-		nil, m.bestIdx,
+		nil, m.selector,
 	)
 
 	if err != nil {
@@ -722,7 +722,7 @@ func (m multi) GenesisDomain(ctx context.Context, domainType phase0.DomainType)
 		func(ctx context.Context, cl Client) (phase0.Domain, error) {
 			return cl.GenesisDomain(ctx, domainType)
 		},
-		nil, m.bestIdx,
+		nil, m.selector,
 	)
 
 	if err != nil {
@@ -742,7 +742,7 @@ func (m multi) GenesisTime(ctx context.Context) (time.Time, error) {
 		func(ctx context.Context, cl Client) (time.Time, error) {
 			return cl.GenesisTime(ctx)
 		},
-		nil, m.bestIdx,
+		nil, m.selector,
 	)
 
 	if err != nil {
diff --git a/app/eth2wrap/genwrap/genwrap.go b/app/eth2wrap/genwrap/genwrap.go
index a6ef58e0b..c4d971c26 100644
--- a/app/eth2wrap/genwrap/genwrap.go
+++ b/app/eth2wrap/genwrap/genwrap.go
@@ -68,7 +68,7 @@ type Client interface {
 			func(ctx context.Context, cl Client) ({{.ResultTypes}}){
 				return cl.{{.Name}}({{.ParamNames}})
 			},
-			{{.SuccessFunc}} m.bestIdx,
+			{{.SuccessFunc}} m.selector,
 		)
 
 		if err != nil {