For me, I am going to say Alice in Wonderland. I understand that some have dubbed it style over substance (it lacks heart, just as The Sound of Music doesn't feature any violent scenes), but I don't care. Perhaps because this movie has sentimental value to me that makes me view it with such fondness. For one, I love the animation and art direction, especially anything Mary Blair (her work is genius). I know that some slam it in comparisson to the novel, but I quite like the adaptation. I admit that some places do actually seem a bit stiff in terms of adapting the original, but the style helps cover this up easily. Alice is my favourite animated feature (tied with Pinocchio and The Little Mermaid, I should add).
Peter Pan is in my number two in these films. The visual style isn't as strong as in Alice, but it is nice and the animation of the human characters is amazing. My only qualms are that Hook needed more screentime and at the Disney staff should not have stopped the "Oh, Tink may be dead" scene so early (they should have included Pan crying out for the children of the world's claps to save Tink, and then we hear claps and laughter set to a choir as Tink comes back to life.).
Cinderella is a little bit hazy in my memory, but probably the weakest of the three. Needless to say, it's still excellent and I can't wait for the platinum edition (less than two months now!
).
I love Spielberg's Hook, but the new Peter Pan that came out two years ago is my fave version so far. 
You know, that "Chocolate" film....