I love so many Disney movies, but my very favorite is The Little Mermaid. The story, the characters, the songs - what's not to love? I can't resist "Under the Sea," "Part of Your World," "Kiss the Girl," etc. or Ariel, Sebastian, Flounder, and the rest. Ursula was a fun villainess.
I just bought 101 Dalmatians and I can't wait to see it again. It's been years since I watched it last. Gotta love Pongo, Perdita, and all the puppies...and ooh, Cruella De Vil is just VILE (of course)!
Aladdin, Cinderella, Lady and the Tramp, Bambi, The Lion King, Beauty and the Beast, and Snow White are other favorites.