Kuja is a pretty good villian, he was more human thn others and showed the selfishness and will to live that humans show.. he just went the wrong way about it, he was also a spoiled brat in my opinion, can't quite remember the story now but I think it goes something like this

Garland: That's it Kuja no more immortality for you
Kuja: Waaaah if I can't live no one will!

And yea the Fight music to Trance Kuja rocks, the start reminds me of that we will rock you song.