I haven't tried the multiplayer, but in campaign I always play as Ratchet (both in FFA and A4O), so it's obvious I would pick "lombax".
Anyway, I don't think I'll play FFA ever again, it's the only game of the franchise that I've finished only twice (once alone and once in co-op). With any other game of the series I was like "Yeah, great game! Great replay value!", but with FFA it was more of a "Meh, let's just get it over with"