For me it comes down to a tough choice between "The Little Mermaid" and "Beauty and the Beast." I think, because of nostalgia, "Little Mermaid" wins.
I also loved "The Lion King," and "Aladdin" is fun too, but I loathe "Pocahontas" and wasn't so fond of the others on the list either.
I think my favorite of the classically animated Disney films, though, is "Lilo and Stitch." Which came slightly after this acme but was a clear return to peak form. I especially loved the character design in that film. The animators drew beautiful Pacific Islander women who actually looked
like Pacific Islander women and not brown skinned Barbie dolls like Pocahontas. The watercolor effect of the backgrounds was perfect, the aliens and space ships had fun designs, Lilo was a strong, intelligent, and realistic -- if troubled -- youngster, and the story just felt very true to me. All in all, a fabulous movie.