I was reading

Is there a filesystem better than others to run EventStore?

I will probably use it on RAID-1

I would say raid-0 with at least a cluster of 3 nodes.
The replication is handled by the cluster itself…

We use ext4 and 3-node cluster. I do not see an apparent need to introduce btrfs or zfs etc. in our setting.

The question is interesting but entirely without context. For example, if running on Windows this is not a concern that can be addressed.

Elsewhere the arguments for using ZFS for Event Store are the same as using ZFS for anything else: it is clearly superior technology to anything else around and should be used where possible. However, if you have no experience managing ZFS based stuff it can be easy to screw up. On the other hand, hardware RAID is plain guaranteed to screw up.