The Beverly! (I'm joking!)
My honest answer, as much as I love to be an adventurous eater, my drink palette could use some expanding. Give me a Snakebite or a Blacksmith from R&C, and I'll be as happy as can be (and probably drunk from just one). But these drinks aren't unique to Disney. Any self-respecting pub should be able to do this (I'm looking at you, "British pub" by my house, who doesn't even have Guinness!)
A lot of the drinks at Disney look neat, but they all seem way too sweet for me.
Edit: a letter