I think both John and Paul's Christmas songs blow. Paul's is "Wonderful Christmas Time" and I can't even think of John's, but it keeps going "So this is Christmas, and what have you <something>?" and then the children start singing, and if I'm not in charge of the tunes, I leave the room/building/county.
Technically, "Linus and Lucy" ("the Peanuts theme") isn't a Christmas song, but it's on the soundtrack for A Charlie Brown Christmas, which is easily the great Christmas album ever.
Ever.