Beer in general. It's probably the most varied alcoholic beverage that there is.
Although recently I've been drinking a lot of red wine and very much enjoying it. Having said that, right now I'm drinking a Tempranillo and it's not so good. Mostly I've found Rioja, Claret and Shiraz to be my favourite varieties, although I've not tried even all of the mainstream varieties since I realised I like red wine.