I'm even more of a sucker for Christmas songs than films. I drive the family mad playing Christmas CDs wherever I go in December. Buy at least one every year. Could also be the singing along that drives them mad.
Hard to pick a favourite, but carol is probably "Silent Night", also "The Holly and the Ivy, when they are both full grown ...", songs "And so this is Christmas", John Lennon, "When my Heart finds Christmas", Harry Connick, jr. "Wonderful Christmastime", Paul McCartney, "Blue Christmas", Elvis and Peter, Paul and Marys' "The Little Drummer Boy", one of the first records my Dad got for his new stereo record player in 1960 something.
The player was in "case" form - turntable in the bottom and two speakers for lid, which separated and unclipped, so you could stand them at the correct distance apart - great "gadget" man, my Dad. We always had the newest "things", like gas powered cork screws, electric knife sharpeners - whatever was available in downtown Castle Douglas. He would have been in absolute heaven nowadays - and probably flat broke.