For film transfers, I would recommend the oldest first. The really early Disney ones depended on the film process to produce the desired effect. The animator a then were smart enough to be able to compensate and even utilize the technicolor process to their advantage. They never intended the final picture to look as the original cels did. Also, that modern roto-scoping was definitely not present until restorations...
So, that being said, I would recommend the original trilogy: Snow White, Pinnochio, and Fantasia (with censored bits restored...).
Good LD transfers of the newer titles would be much appreciated though, Andrea. I think the Little Mermaid, Beauty and the Beast, Lion King, and Aladdin could be feasibly restored to their original state by combining LD and BD sources (CD too for Aladdin). It would be quite an under-taking but more possible since there were not as many "restorative techniques" applied.