With Sierra Nevada getting close to full operations at their new East Coast brewery in North Carolina, I wonder if they are going to try to get a contract with Disney... While their more recent new items have been a little less interesting than they were years ago, I still place them quite a bit above Sam Adams in terms of interesting flavor profiles and I would be very happy to see them at Disney.
Obviously, I'd love to see breweries like Stone and Dogfish Head (or to keep it local for me Flying Dog), but as
@Phonedave said, even those craft breweries who are top 10 or so in production don't have the facility to keep with the demand of Disney.
I really think that Sam and Sierra Nevada and maybe New Belgium are the only ones who could keep up with the demand of a regular Disney contract.
To the OP question - the Unibroue beers in Canada are my favorites on site but sadly you have to eat at the Steakhouse to get most of them, or go during Food and Wine. During Food and Wine, I do love the Innis and Gunn at Scotland (which I am very happy to now be able to get locally).
If I can digress into personal Disney history, my first foray into craft beers was actually at Disney back in the early 90's. There used to be a bar called the Catwalk Bar at MGM above what is now the Playhouse Disney show. It was my favorite out-of-the-way place to relax. They had a pretty wide variety of beers both on tap and in bottles. I know I had Unibroue's Fin du Monde and Raftman there on tap and Blackened Voodoo and Brooklyn Brown among others in bottles.