It'll depend largely on how early/late they come into the game and also how they are in battle.

I want to say Sazh, Vanille and Lightning. But I think it'll end up being Snow, Vanille and Lightning because I tend to avoid guns, and tend to enjoy those that use fists/feet when attacking. Maybe Vanille will lose out to Fang, too, but we'll see.

I'll avoid Hope, though. Another tendency in FF games is that I hate playable children characters.