I based my answers off of a purely simplistic definition: if I felt the characters were motivated for the lust for personal power solely to benefit themselves, as opposed to following an ideal or seeking answers.

Under that reasoning, I felt that Hojo was in it more for his own glory of discovery than purely for the advancements of 'science overall,' that Garland's conscious manipulations were slightly more calculating than Kuja's understandable desire for life (it's been a while since I played the game, so my impressions are blurry), that Yu Yevon and Seymour both followed their own opinions of salvation for their people/the world (and Sin was only a tool) so none of them were really the villain to me, and I totally misread the options of FFXII so I somehow neglected Vayne, or else I would have picked him.

So oddly, my opinions of the villains in Final Fantasy really revolve around 'placing one's self above one's chosen group,' where group can either mean actual physical people, or a general ideal that's bigger than just a single individual. I'm so stereotypical!