Why ReiserFS? It's pretty much a defunct filesystem at this point. It's not really in the same class as ZFS and Btrfs, if you want a third option maybe look at HammerFS? Although I think pretty much everyone is waiting for Hammer2.

There was a talk "Why OpenBSD sucks" by Henning Brauer, where he complains that ZFS is a "kitchen sink" approach to a filesystem. He doesn't really explain further, but it would be interesting to hear someone elaborate that criticism.