[iforgotpassword]

The two most obvious reasons to assume so are that btrfs is in comparison relatively new and quite complex. Not to say zfs isn't complex, but I'd rather trust zfs just because of its age.

That being said, unless I really need those specific features, I go for ext4 whenever possible, as it has to be the most battle tested one, at least when it comes to *nix. It also seems that fsck.ext4 has almost magical powers sometimes, but that shouldn't stop you from making backups obviously.

Related: http://events.linuxfoundation.org/sites/events/files/slides/...