Just wanted to say that Jenova is an anthromorphic being whose gender is by appearance female. However being anthromorphic and being able to essentially shift its essence to suit it means it technically has no gender or hermaphroditc or we ca simply accept that it can be both male or female depending on desire.
Also Sephiroth feats. I am going to have to give him the ability to fly through space. His abilities to fly are not related to his wing. It is not done through physical means as a single wing such as his cannot fly at any speed approaching what he can do let alone fly in a straight line.
Malygos is not as all powerful as you are all making him out to be. If he was then there would have been no need for him to help create the demon soul in the first place. If he was able to channel all the magics of Azeroth as he was implicated in being able to manipulate using the Nexus (not necessarily his own power) then he could have obliterated the burning crusade entirely on his own.
ALSO THE DESTRUCTION OF REALITY THING WOULD HAVE TO BE BLOCKABLE. If it wasn't why didn't he just use it on Sargaras it's a big enough target and nearly impossible to miss.
Malygos is powerful but Sephiroth simply has more useful combat feats and defeated enemies to guage his strength by. Malygos has a few very powerful combatants but has nothing that can compete with directly threatening the existance of a planet in a single move in such a short period of time i.e. Meteor vs. Nexus leyline conversion.
Seph for the win.