ZFS is native, VxVM is 3rd party
ZFS costs $0, VxVM costs a lot of money in licenses.
ZFS is fully supported within your Sun contract at no extra charge.
Performance-wise, the only advantage for Veritas is Veritas Cluster. As simple disk manager, ZFS is much easier to use and manage.
I would go with ZFS personally. It is much easier to manage. I'll put it this way. Take note of the native solaris device files:
zpool create newpool mirror c0t0d0 c0t1d0
This creates a two way mirror, creates a file system on it and mounts it at /newpool.
Here is how easy it is to create a RAID5 volume, creates a filesystem on it, and mounts it:
zpool create raidpool raidz c0t0d0 c0t1d0 c0t2d0
I am not kidding. It only takes one simple command to create a ZFS volume. You can also move external storage devices between different machines with ZFS, create disk quotas, reservations, integrate with Solaris containers, take snapshots, track io statistics, and many other cool things. ZFS is very simple to use, flexible, and cheap. In my opinion its only shortcoming is it doesn't have built in backup and restore tools like ufsdump and ufsrestore (I dont con't zfs send and receive).
