1. White Mages

I pick both. For the win.

2. Attackers

Quina with Twister, Earth Shake, Limit Glove and all of those utilities. Vivi is neat, as well.

3. Others

Generally I'd like to keep Zidane, but in Memoria and Crystal World (where you CAN kick Zidane from your team), I use all the mages: Eiko, Dagger, Vivi and Quina.