This is probably a thread that happens every Christmas season (maybe multiple times), but I'll go ahead anyway.

Here are some of my least favorites:

All I Want For Christmas
Wonderful Christmastime
Santa Baby
Last Christmas
Christmastime is Here (I know Charlie Brown's Christmas is a beloved classic, but I don't like this song)
So This is Christmas

Honorable mentions or bad versions of songs I otherwise like:

The Ronette's version of Sleigh Ride (I love Sleigh Ride, but hate their version)
Jingle Bell Rock


There are probably more, but that's all I can think of right now.