I like Mediaeval carols and not so well-known ones–old German carols–advent carols–anything but “Jingle Bells” and other done-to-death modern secular carols. Here are three you don’t hear that often:
The Boar’s Head Carol
Maria durch ein Dornwald Ging
Leise Rieselt der Schnee
The first is gay, the second is somber, and the third is poetic.