Well Lionlake, last time i made an argument about this on G-Masters, some people got extremely pissed as i completely ruined their 'favourite game' Final Fantasy VII, by saying that it was a very cliched, stereotypical game, that wasn't very good at all and simply targeted a popular audiance. They obviously couldn't find anything good about Final Fantasy VII, and in the end, well let's just say some people were crying lol :P
So put it this way, Sephiroth was a stereotypical, good guy, gone bad case, who didn't have any part of him that made him anymore evil than the next villian and he had even been good at one point. Don't think i'll go any furthur, i hate Final Fantasy VII with a passion so i don't want to start anything.
And Lionlake FF6 had Kefka as the most evil hero, and damn it, he was the most evil, i never saw his twist coming. On the other hand Final Fantasy VII was ridiculously predictable and i was only about 10 when i first played it.