Jungle Book
Aladdin
The Lion King
I was huge fan of The Jungle Book growing up, loved Baloo and knew all the words to the whole movie. I was over the moon when my primary school did Jungle Book as the school "play" and I got to be Baloo, maybe partly because I already knew all my lines!
Aladdin and Lion King were just both really impressive to watch at the time. They have some of the best songs and visual design. The plots, although some may not like the more "blockbuster" type pacing, at least never really drag. If I was asked to pick two other Disney movies to watch, it would be those.
That being said, having loved Jungle Book so much as a kid wearing the tape out and having a child of my own and ending up watching the other two so much, I could go without seeing any of them again for a while!