Oh man, toughest question I've had to answer on these forums!!!
Mickey has long been one of my favorites, especially in his sorcerer role.
From the movies...ugh, this gets too difficult. How about I go with two who you can't really separate from each other...Lumiere and Cogsworth.
Those two could have had their own spinoff. They are the perfect duo, especially how their personalties compliment each other.
Sebastian has always been a favorite of mine as well.
Villain-wise...gotta go with Ursula. When I saw Little Mermaid as a 3 year old in the theater, I named her as my favorite character. My entire family was concerned about me since my favorite character was the villain!! My rationale: she's big, she's powerful, and she can steal voices!! (Seriously, what kid didn't want to steal someone's voice at one time?)