• Are you just healing? Then the former is better, though Zabran's Tempest is even better.
• Are you just nuking easy stuff (like powerleveling)? Then the former is better.
• Are you just nuking hard stuff? Then the latter is better.
• Are you doing a bit of both? Then use your best judgement.

The restore MP proc only works when you melee with the Mog weapon (auto-attack), so don't put too much stock into that.

Lots of people just use Chiran Zabran's Tempest because it's the best pure-healing weapon.