My favorite traditional animation is SLEEPING BEAUTY.
I also think FANTASIA is a masterpiece of drawing, but I find it difficult to get through the entire movie without feeling sleepy. Every individual segment is astonishingly animated and beautifully scored, but the whole thing is a too rich dessert.
And all of the usual suspects from the 1940s: PINOCCHIO, BAMBI, and DUMBO. It doesn't get any better than those films. And BEAUTY AND THE BEAST, THE LITTLE MERMAID, and THE HUNCHBACK OF NOTRE DAME feature the best of modern animation techniques.