Aladdin is by far, my all-time favorite. It has the best songs of any Disney musical.
Robin Williams was hilarious as The Genie (One of my favorite Disney characters) The villain, Jafar, had a sinister character design that I loved, and to top it all off: Gilbert Gottfried.
Beauty and the Beast is a very close #2. (I saw it several times in the theater as a kid) I think, as a film, it is superior to Aladdin. The intro really makes the movie feel like a fairy tale.
B&TB is a more dramatic, smarter film that feels more grounded than any other Disney movie.
But Aladdin is still my favorite, because it's more fun to watch.
Others I enjoyed:
-The Great Mouse Detective
-Ducktales the Movie: Treasure of the Lost Lamp
-The Rescuers Down Under
-The Brave Little Toaster
-101 Dalmatians
-The Sword and the Stone
-The Many Adventures of Winnie the Pooh
-A Goofy Movie
-The Emperor's New Groove
-Wreck-it Ralph
As a gamer, I loved Wreck-it Ralph. So many little touches to Ralph's game, Fix-it Felix Jr, really made it feel like an actual game you could have stumbled upon in the 80s. The cameos were great (I am a huge Sonic the Hedgehog fan, so it was cool to see him & Eggman appear. Ralph picking up the exclaimation point from Metal Gear put a smile on my face too)
The Hero's Duty sequence looked incredible on the big-screen, and King Candy was one of the best Disney villains in years. I just wish Sonic had some more lines and there were more recognizable faces at Bad-Anon (Wario, Sephiroth, Shadow the Hedgehog, one of those construction-helmet guys from Mega-Man)
I also liked those Roger Rabbit shorts that played before Disney films. Tummy Trouble, Roller-Coaster Rabbit & Trail Mix-Up.
