Even though its been said already, Ill say what I use most.

Tyrannosaur: Boost his magic and he can easily deal 9999 to everything on screen.

Yojimbo: This ones cool because it does Leos Shock attack.

Stray Cat: The Cat Scratch attack, even though its supposedly toned down, still deals massive damage. Theres not much arguing with a level 30 Gau hitting for 6000 damage per round.

I mainly use Tyrannosaur for the Meteor but I like to have fun and try all different kinds of rages. Sometimes you can find some pretty interesting ones.