Since I revived the "Least Favorite Carol" thread, I felt I should bump this too!
Mine is still Carol of the Birds
http://www.youtube.com/watch?v=LE0yEf7O8Dk
but there are 2 new favorites:
Third Day's "Do you Hear What I hear?"
http://www.youtube.com/watch?v=m9ioc0gTnH0
and
Casting Crowns' "I Heard the Bells on Christmas Day"
http://www.youtube.com/watch?v=M7670CXvPX0