Well, Raebus wins the prize for most childish arguing.
From what I've seen of this thread, it seems a lot of people are judging this entirely on magic power, while I'm inclined to agree with those of the opinion that Seph would slice him to pieces in a one-on-one fight.
And I think destroying a few towns and gauging a few scars on the surface of a planet not quite up to the same level as the ability to manipulate all the life force of a planet into killing a great many people and turning the entire planet into a moving vessel to travel the cosmos and no doubt spread such destruction among other places.
And lets not forget that Kefka had to use the statues to gain his power, while Sephiroth with his own power gained control of Jenova and the Lifestream to start his Geostigma plan.