I have always loved Josh Groban. His voice is amazing. His Christmas album Noel is no exception.
I think Mannheim Steamroller's Christams CD's are also the best. My kids' favorite is their "Rudolph the Red-nosed Reindeer." They just hit "repeat" when they comes on. Their music is great "clean the house" music.
But I think my most favorite Christmas song is a fairly new one and is called "Mary Did You Know." When my brother was in college he was in the choir, and we went to his Christmas concert, and that is the first time I heard this song, and I just fell in love with it. I love the pictures this video puts with the music. This version is done by Clay Aiken. Enjoy!