Well...the highest ranking Christmas carol of mine is We Need A Little Christmas, but it is the version by the New Christy Minstrels. That is number one, the others are not in any sort of order.
Christmas Canon Rock by TSO
I believe in Santa Clause Dolly Parton and Kenny Rogers
Hard Candy Christmas Dolly Parton
Silent Night performed by Carlos Nakai
I couldn't believe after I finished my post that I forgot some of my all time favorite songs, and they happen to be Christmas, sort of.
A Christmas Festival, performed by The Boston Pops, and conducted by Arthur Fiedler
A'Soalin'/Esa Enai
Song for a Winter's Night
First Snow
Lord of the Dance
These last four are all on a particular album together and are phenomenal, at least to me. Sarah Mclachlan just released a version of Song for Winters Night. I've heard it and am not moved to vomit, but, it isn't the same. I will probably add more, I love Christmas music.