In Disney there are many villains, from the ones who you understand (Scar, Ursula – jealousy), to the ones who deserved what was coming (Gaston).
But, the question here is this – which villain would have succeeded if it wasn’t for the fact this was Disney? In real(ish) life, who would have actually been victorious?
I’m going to put aside the Disney stories based on real(ish) life, such as Pocahontas and Robin Hood, because they are real(ish) so it could be suggested that they had their fate controlled by powers outside of Disney – Ratcliffe probably would have ‘succeeded’ and John did rule for quite a while.
So, I believe that the Evil Queen would have succeeded, she had the most logical approach to her evil plan. If it wasn’t a Disney movie, then the true love which broke the spell wouldn’t have done anything and Snow White would have remained disposed of.
Plus, Regina is pretty awesome on Once Upon a Time.