I believe, DFS replication is meant for files synchronization not for the databases. consider following options as database solutions/features in SQL Server.
Since you already have SQL FCI in-place, the databases and data (program files) related to SQL Server are already in shared location which can be accessible to both nodes.
Unlike FCI, availability groups hosted by stand-alone SQL instances, each instances called as replica, every replica maintains their own copy of databases and every change in the database replicated all database copies across replicas within a group. you can have 8 replicas, required enterprise license. WSFC required for auto-fail-over purpose.
Log shipping works based on scheduled backups, which periodically backups the changes on primary server, secondary server copies backup files and restores regularly as per defined schedule.
Above options considered as high availability solutions, but replication is something used for copying and distributing the database's objects