My absolute favourite Disney animation is the Lion King (include the Lion King 2, too) <33
But it's not the only one. The others I really like are The Jungle Book, Treasure Planet, Lilo & Stitch, Mulan, Brother Bear and The Emperor’s New Groove.
The Goofy Movie because it shows a beautiful father and son story that teacher you that no matter how old your kids become, is important to be part of each others lives.
If this question was asked when I was a little girl I would tell you Little Mermaid, Cinderella, Pocahontas.
Now, I would say Tanged, Hercules and Mulan!