X is my favorite FF, serious(shot
And Kefka broke many of the rules villains usually follow, he actually succeeded in destroying the whole world, he did MUCH MUCH MUCH more evil than killing a pretty main characted(looking at a certain someone), he is the no holds barred, no morals at all type, he was immune to talk no jutsu to his last breath, he doesnt contradict himself or gives us a lot of confusion.
But most of all his laugh... Omg dat laugh is the most memorable thing ever about FFVI, his theme and any music to do with him and the final fights all deserve mentioning.
Even though he's so simple, that in a way makes him unique, fresh and special. I actually really really hated him when I was playing through FFVI, but then again isn't that what a villain is supposed to achieve, Kefla really nailed it on the spot there.