XFS is supported by effectively every distribution and has very significant development each release (even the test-suite for all filesystems is called xfstests

XFS is supported by effectively every distribution and has very significant development each release (even the test-suite for all filesystems is called xfstests because it used to be only part of XFS). And despite being older than ext (and older than Linux itself), XFS has lots of features which ext doesn't have -- such as reflinks and CoW (though XFS also doesn't have ext4-style encryption).