I've collected what I think is a fairly comprehensive list of the most popular Christmas songs. I'm not including ones that are silly (The Night Santa Went Crazy, Hippopotamus For Christmas, etc.) or ones that have basically only one rendition (Christmas Don't Be Late, All I Want For Christmas Is You, You're a Mean One, Mr. Grinch, etc.) These are about the songs themselves, not so much who sings them.
I really like "Have Yourself A Merry Little Christmas," for some reason. I can't stand "Rockin' Around" as sung by Brenda Lee, but there's a cover of it I've heard that's not so bad.
Feel free to mention a song I left out. I'm sure there's at least ONE.
The List (Too many to make a real poll out of, as I find out after entering them all in... weak)
- Angels We Have Heard On High
Away in a Manger
Carol of the Bells
Deck the Halls
Do You Hear What I Hear?
Feliz Navidad
Frosty the Snowman
God Rest Ye Merry, Gentlemen
Hark! The Herald Angels Sing
Have Yourself a Merry Little Christmas
Here Comes Santa Claus
I Saw Mommy Kissing Santa Claus
It's Beginning to Look a Lot Like Christmas
It's the Most Wonderful Time of the Year
Jingle Bell Rock
Jingle Bells
Joy to the World
Let It Snow!
Little Drummer Boy
O Holy Night
O Little Town of Bethlehem
O Tannenbaum
Rockin' Around the Christmas Tree
Rudolph the Red-nosed Reindeer
Santa Claus Is Coming to Town
Silent Night
Silver Bells
Up on the Rooftop
(There's No Place Like) Home For The Holidays
The Twelve Days of Christmas
We Wish You a Merry Christmas
Winter Wonderland
White Christmas