Zootopia: This isn't just my favourite Disney Animation Studios film, but my favourite film period. I went to see it in the cinema more times than I have with any other film and while Disney haven't marketed it nearly as much as they should have given its success, I've still amassed a decent enough albeit not huge collection of merchandise as well. Amazing chemistry between the two leads, brilliant allegory and some if the best world building I've ever seen.
Fox and the Hound: Easily the most underrated Disney film. A bittersweet story about social conditioning and a friendship that cannot be with an ending that isn't entirely happy and what in my opinion is one of Disney's most heart wrenching scenes, when Widow Tweed leaves Tod in the game preserve for his own saftey.
Beauty and the Beast: Easily the best of the fairly tale/princess films (never been a huge fan of the latter term) this one doesn't really need a lot of explanation. I'd consider it Disney's most romantic film and the musical numbers and songs are all memorable. The score by Alan Menken is one of the best in any Disney film.
Tarzan: This was the final film of the original Disney Renaissance and I wish it got more love. I love the arc Tarzan goes through and even its comic reliefs are great characters, Terk in particular. Even if I did think that she was a he when I was younger
Still, I love the songs by Phil Collins, and it was an interesting touch to have the film's primary singer be a narrator essentially, the film only having one full blown musical number.