Had some of this when I was in Boston last month.............good Lord. http://salumeriaitaliana.com/catalog/cheese/aged/cacio-di-bosco-truffle-cheese
White American is what most Mexican restaurants use to make their queso dip because it melts down very nicely (try melting chedder into queso dip, doesn't work well), just add a little heavy cream and some green chiles and you're good to go. It's relatively cheap and you get the classic blanco color. Some grocery stores only have them in prepackaged singles, still works.
I like most of what's been posted already, especially the smoked stuff, but for the past couple of years my favorite remains: SO smooth. You can't get the flavor & texture out of your mind, & it's hard to stop!
Manchego FTW!!!! The best I've had was a from a Publix store in Chattanooga...Corazon de Rondo or something like that...It's best when thinly sliced, razor thin...its just heaven...
