My leaders are Mog, Terra, Sabin. The parties vary but here is a usual breakdown:

People who auto-fight so I can spend time charging SwordTech party:
Mog
Cyan
Shadow
Umaro

Lore learning party:
Sabin
Gogo
Strago
Relm

The kick-ass party:
Terra
Locke
Edgar
Celes


I try to make sure each party has the ability to steal.