Favorites: Oh Holy Night and Silent Night.
I don't know what's the matter with me, but I WEEEEEEEEEP when I hear those two (ok, maybe not weep, but tears trickled down my cheeks without fail).
Least Favorites: Little Drummer Boy. I particularly dislike the Bowie/Crosby duet version, even though I love both of those singers individually. But that rendition just creeps me out.