Hmm, wow this is a tough one, based on the options, I'd go with the Beauty and the Beast, as I grew up in a "small provincial town." I could really empathize with Belle and her dream of escape. And then you throw in the main plot about finding yourself in spite of your appearance, the lessons about vanity, pride, and arrogance. (Remember it was the Beast's own vanity, turning away the beggar woman because of her looks, that caused his damnation.)
However, for technical achievement, I'm going to go with Snow White and the Seven Dwarves, for being the first cel animated feature film in motion picture history. Simply put, it was the very first animated movie where every frame was hand drawn.
For story... from the entire list... I really don't think I can think of any Disney movies which stand out from the others as being the best. I can think of a few which are bland and uninspired, especially in recent years, But I don't know. Lion King, Robin Hood, Mulan, Aristocats, Aladdin, Black Cauldron, Snow White, Beauty and the Beast, Bambi... each of these and others I can't think of are truly timeless classics, movies that I will definitely be passing along to my children, should I have any.