I enjoy the traditional Christmas music, like "The Messiah" and the ones that choirs like to sing. For the 20th century classics, I really prefer them by the singers who made it popular the first time. Like "White Christmas" by Bing Crosby and "Holly, Jolly Christmas" by Burl Ives, "Rudolph the Red-Nosed Reindeer" by Gene Autry.
I also enjoy the silly and irreverent Christmas songs, like "Grandma got runover by a reindeer" and "The Night Santa Went Crazy".
