Since I could choose multiple characters ... I did.

Cecil was an excellent main character, with his triumph over his evil past and such. Plus, when he first becomes a Paladin, he can gain like five levels in one battle. It was awesome.

Rosa was a good heroine and a good white mage. Plus, magic wasn't all she could do -- her Aim skill came in handy quite often, and could do some pretty decent damage on some enemies.

And I don't think it would be a stretch to call Rydia the best black mage in the series. Not only could she cast black magic, she could also summon -- which is more often than not what I use, considering the delayed casting time of many of the more powerful spells. I like that she is powerful enough without any side-quests to add to her list of summoned monsters, but you have the option to venture out and pick up Odin, Bahamut, Asura, Leviathan, and the Sylphs. (I don't care about the pathetic Goblin, Mindflayer, and Cocatrice.)