There's no experience cap.
My favorite party which I always seemed to gravitate to, no matter how often I played, was:
Nameless One
Morte
Dak'kon
Annah
Fall-From-Grace
Nordom
I preferred Nordom as a ranged fighter to Ignus, because I used the lens that made Nordom extremely hard to hit; and because I preferred the extra effects that some of his bolts had. It's purely a matter of personal choice, but remember, too, that if you have Ignus in your party, Vhailor is out. Both can't survive in the same group, for long.
Morte: His taunting feature is fantastic. I actually used it to prevent Tria from casting on my party, while everybody else whaled on him.
Annah: IMO, she develops into a great party addition, becoming virtually a ninja over time. I sent her into a few dungeon areas entirely on her own, where she was able to pick off all the monsters one by one, without any aid. Hide, attack, run, hide, attack, run, etc. One tough broad, as the saying goes.
