From this list I have to go with Maleficent; she has some of the best lines in villain history:
"Oh, they're hopeless. A disgrace to the forces of evil!"
"Now you shall deal with me, oh prince, and all the powers of [Heck]!"
I also have to give props to Lady Tremaine from
Cinderella. I've known too many people like this, who are just horrible abusive bullies. To this day I feel Cinderella's pain. And the writers/animators really knew what they were doing. When we realize in the end that Cinderella has the other slipper, the next shot is of Lady Tremaine's shocked reaction and we know she's been defeated. Perfect moment!