Hmm...

Independent: Long Range is pretty cool, and so is Luck Plus, just because you're that much more lucky.

Support: Added Effect. Add it with Hades in Cid's Scimitar - you have 3x AP and instant status carnage!

Command: Enemy Skill - so versatile. And Mime, because Mime is awesome in the Battle Arena.

Magic: Contain. Obviously a favorite - the spells just rock.

Summon: Choco/Mog! Can you say Fat Chocobo?