I need to play FFVII and VIII again to reanalyse Sephiroth/Jenova and Ultimecia, but as it stands, Kuja is my favourite, mainly because he has real reasons for doing what he does, also, like Mo, I like Kefka too, hes also hilarious. I cant wait to see the new translations for FFV and FFVI, they just might make Kefka and Exdeath/Exodus a lot cooler. I always liked Exdeath/Exodus, he always just seemed so powerful, always blasting the party and wiping them out most of the time, and he just seemed unstoppable, I was actually a little scared when I had to face him in his castle, but that was YEARS ago.
However, my favourite villain isnt in FF