Which Villain Accomplished The Most?

[Serapy]

I would say Kefka, since he did manage to accomplish all of his goals except for the end of the game when he tried to end all life. Of course the heroes absolutely had to win at that point.

Ultimecia, she has been alive for most years, probably since the creation of mankind in the game.

Where is the proof of this?

As far as I know, there's no proof that how long has Ultimecia been alive, how long has she been achieving her goals or how many goals has she succeeded, either, unless you show me the proof. So it's pretty much self explanatory. And yeah, time compression was indeed awesome, I could say it's pretty overpowered.