Without a doubt, the best Christmas carol is Good King Wenceslas.
a) It’s a pretty tune.
b) It represents for me the spirit of Christmas. “Ye who now will bless the poor, Shall yourselves find blessing.”
La franchise ne consiste pas à dire tout ce que l’on pense, mais à penser tout ce que l’on dit.
H. de Livry
“Carol of the Bells”
“God Rest Ye Merry Gentlemen”
It’s a long way to heaven, but only three short steps to hell.
“We Three Kings”
I liked the bit about “following yonder star” and the last verse about “suffering, sighing, bleeding, dying” always seemed so weird to have in a holiday tune. I like weird.
“Emmanuel”
At least I’m assuming that’s the name of the one that goes “rejoice, rejoice, Emmanuel has come to thee, O Israel”. It’s a pretty song, and it’s my mother’s favorite too.
“Walking 'Round in Women’s Underwear”
Just simply hysterical.
“Happiness is nonetheless true happiness because it must come to an end, nor do thought and love lose their value because they are not everlasting.”
Happy Christmas(War Is Over)
John Lennon
“All I Want for Christmas is My Two Front Teeth.”
This space for rent.
Ave Maria for it’s beauty and power to inspire piety and mercy in someone who’s never pious or merciful. Harry Connick Jr. does a great rendition of this song.
The Little Drummer Boy for its simplicity and for the way it can pull those heartstrings.
“Teaching without words and work without doing are understood by very few.”
-Tao Te Ching
I Must second Tennhippies choice. Also,I like Little Drummer Boy.
No, it’s officially a Christmas song, but after spending one Christmas deployed, Belleau Wood by Garth Brooks has special meaning. I have sung Silent Night/Stille Nacht auf Deutsch with German friends.
I also have to mention Mary, Did You Know by Kathy Mattea, since it’s a little off the beaten track.
For traditional ones:
O Holy Night big John Wallace (kudos to anyone who knows what I’m talking about)
Have Yourself A Merry Little Christmas Karen Carpenter
Sue from El Paso
Experience is what you get when you didn’t get what you wanted.
Carol of the Bells. It’s so spooky, I love it.
I was going to say that my favorite Christmas carol was that bell song, and the name of it was on the tip of my tongue, but now my memory has been refreshed! Carol of the Bells. Thanks folks!
I also love that one about wassailing. 
“Christmas Time is Here” – It’s the slow, jazzy number on A Charlie Brown Christmas. I don’t know if Vince Garibaldi wrote it, but it he plays it well.
Mr. K’s Link of the Month:
Oh Holy Night and Oh, Come, All Ye Faithful. And Away in a Manger.
I dearly love “It Came Upon The Midnight Clear,” especially the third verse that nobody ever sings. My all-time favorite, with “Joy to the World” a close runner-up. Nothing closes out Midnight Mass like “Joy to the World.”
Catrandom
I love Little Drummer Boy…Sister Soliel’s version is really cool, in case anyone knows who they are.
I just love Christmas carols in general…I’m a big sap at Christmastime.
“…all the prettiest girls live in Des Moines…”
–Jack Kerouac, On the Road
Do You Hear What I Hear. There’s no contest.
-Lanna
Gosh, I like a lot of them, but my favorite is “Silent Night.” Done very simply, esp. by children. No Mariah Carey treatments.
Honourable Mentions to:
“Greensleeves” - instrumental
“Oh Holy Night” I love Andy Williams’ version of this song, believe it or not.
“Breath of Heaven” by Amy Grant
“Veni, Veni, Emmanuel” by Mannheim Steamroller
“Do you Hear What I Hear?” by Vince Gill
“Santa Claus is Coming to Town” live version by Bruce Springsteen - I love hearing Clarence Clemons (sp?) crack up as he ho-ho-ho’s.
Majormd et al –
Being deployed, this is a gimme:
“I’ll be Home for Chrismas.”
Funny - Christmas at Ground Zero by Weird Al
“normal” - Carol of The Bells… I just like complicated music.
http://www.madpoet.com
The early bird gets the worm, but the second mouse gets the cheese.
There’s only one choice:
Deck us all with Boston Charlie
Walla Walla, Wash, an’ Kalamazoo
Nora’s freezing on the trolley
Swaller dollar cauliflower alla-garoo!
“East is east and west is west and if you take cranberries and stew them like applesauce they taste much more like prunes than rhubarb does.” – Marx
Read “Sundials” in the new issue of Aboriginal Science Fiction. www.sff.net/people/rothman