I find Wakka is my best.

His attack reels is just to good to pass up.

I often use a combo of Entrust with Wakka to use his attack reels, really helped against Neslug, or Omega weapon (very easy just had a load of heath in PAL version)

I found Auron the most usless, sure he has lots of heath and can hit hard, but his Accuracy is very low, and he is also slow and his overdrive is nothing to sing about, and i don't like his Celestial weapon.

The high damage when on low heath thing really stinks as i often try to keep my party healed.

Lulu can be fun with her Celestial weapon, throwing out double ulitimas with magic plus is fun and i like the Onion Knight.

Be fun getting a mini-Malboro