If you're talking about general music, I have been listening a bit to Jeff Buckley's rendition of "Hallelujah." It's a pretty good song, although it took me a few listens to really comprehend the mature nature of the song's lyrics.
Now, in terms of Christmas music, the song I have been jamming to would be "Snoopy's Christmas" by the Royal Guardsmen. It is pretty good, reminds us all of the Christmas Truce of 1914, the instrumental part is pretty nice as well, and the vocals seal the deal. ^^