These are totally different solutions implemented to solve different issues. Failover cluster is for business continuity and H/V replica is for disaster recovery. So they are complimentary to each other rather then competitive approaches. Both can failover VM from one physical node to the other but H/V replica does lose some data and does not do transparent failover (cluster does not lose data and does transparent failover from the other side). Also cluster does not put that heavy load on the network as it uses shared storage. H/V replica does not use shared storage so it has to synchronize all the changes over the network. So if you have very flexed RTO/RPO then you can simply skip using cluster (and maybe a backup app as well) and use only H/V replica. However if you want a guaranteed uptime and flexible recovery process you need all of them: replication, cluster and backup.
From : Microsoft Form .
https://social.technet.microsoft.com/Forums/systemcenter/en-US/eabf3632-5b0a-4167-97be-faa1b97d63f3/hyperv-replica-vs-failover-cluster?forum=winserverhyperv
