I'd say they're all great, if not all the same. (People say that Kefka is so much better than Sephiroth, even though they're exactly the same, bar looks and personality.)

Ultimecia was very well done. People say she doesn't have character, but they must be too blind to pay attention to the story, or something. Ultimecia is alot like Zemus in that regard.

Zande had neat hair.

Garland was awesome for the Time-Loop thing.

The Emperor just looks plain cool.

And who can resist Kuja?

So basically, I can't really decide. But I do really like Seymour.