Amazing: Basically anything Clamavi De Profundis; it's really powerful stuff.

Three of my favorites from the above playlist: God Rest Ye Merry Gentlemen, We Three Kings, and Christmas Medley.

As to what I hate, most of the stuff they play in stores; it's usually sappy and just feels a little slimy, and I know it's driving the employees crazy too. Not pleasant, although occasionally you'll hear something awesome. But that's pretty rare.