[seefriek]

XFS is better than ext4 when:

1) You need huge filesystems (like 100TB+). 2) You need huge numbers of files per directory (in particular, XFS is much faster at creating the files). 3) You have a workload heavily skewed toward streaming data off the disk.

ZFS does 1 & 3 well. Not as good on 2. And it's less mature on Linux than the other 2. But ZFS also has much more robust data integrity feature than either ext4 or XFS.

P.S. - I migrated most of my stuff from XFS to ZFS this year after many years of using XFS (back when IRIX was a thing). P.S.S. - Never run XFS without battery backup and make sure to force sync data to disk periodically.