I fairly recently dove into Disney Villainous and bought the base game and both expansions [looking forward to the new one next month!] and my wife and I have been pretty obsessed ever since. We've barely played any other games since we got it. I love asymmetrical games and I especially love discussing power levels of everything in an asymmetrical game, so this is just a for-fun discussion and is not meant to be taken seriously.
This is all based on anecdotal experiences and 95% of our games are 2-player. I won't go into too much detail in this opening post but I'd be happy to discuss my thoughts on any of them. The Queen of Hearts has nearly a 100% winrate in our 2-player games, so we tend to not play her anymore although I do find her quite fun to play. My favorite character is easily Hades but he's unfortunately middle of the pack I'd say, the game is wonderful but I do not think the balance is perfect as there are some villains that just have a way more streamlined and quick path to victory. I think I'd rank the villains like so:
S-Tier:
Queen of Hearts
A-Tier:
Dr. Facilier
Maleficent
Captain Hook
Prince John
Ratigan
B-Tier:
Scar
Evil Queen
Hades
C-Tier:
Jafar
Yzma
D-Tier:
Ursula
The definitive Disney Villains tier list! from Schaffrillas