Setzer by far. I hated Cait Sith. I was glad to see him die in the Temple of the Ancients and throroughly pissed when I saw him come back. The only time I have him in my party is that part in Junon where you're required to do so.

And Lady Luck's only decent options were Two Dice and Four Dice, which you should learn first if you're going to have her in your party.