Cait Sith is the best Wizard after Aeris bites it, he has an incredibly relevant final weapon, and his Limit Break is the first attack in the game capable of doing 9999 damage. He is -Much- better than Tifa and Vincent.
After all this tossing with crap characters, I can't remember who I used.... I liked Red VIIIth, he *looked* cool, and Cid was the man. I think I used them....for non stat related reasons.