I'm too lazy to key-in an explanation on the pros and cons of each of those file systems, but in short XFS is the one to choose. What is "best" is also subjective and determined on your use and preferences.
Agree with chunkymonster, it depends on your use and preferences. Basically the selectable file systems allow ur NAS unit to adapt to all types of networks. But if you want volume snapshots, you must use ZFS.