I'm a holiday junkie, from about the week before Halloween through about the first week of January, so I have no single 'favorite' Christmas movie. It all depends on what I'm in the mood for at the time.
On the short list of my favorite
s, you will find (in no particular order):
It's a Wonderful Life
A Christmas Carol (George C. Scott as E. Scrooge)
White Christmas
A Christmas Story
The Christmas Sweater
Jim Carrey's/Ron Howard's How the Grinch Stole Christmas
MGM's cartoon of How the Grinch Stole Christmas