If anyone ever really paid attention while playing FF VII, you'd realise that you never actually fought Sephiroth until the end. The entity that appeared to be Sephiroth throughout the game was actually Jenova.
Ps Red 13 had a better chance with aeris then cloud did =D
When I think of great video game villain, Seph doesn't even come to mind (androgynous male with katana blade attached to some crazy Janpanese out-there plot -- sounds like a bunch of anime cliches rolled into one). If we are talking FF villains, I would much rather have Kefka; at least he was funny, even if he was sort of a Joker rip-off.
COME ON, PRINNY FOR PASBR!!
Well if Sephiroth was the final boss, then it'd make the inclusion of a playable Final Fantasy character (somewhere down the line) less likely.
Plus I don't think Sephiroth is all-encompassing enough for a final boss, he's only part of one series of games. I actually think Polygon man is near perfect, besides the fact that he's a little bit obscure and exclusive to America.