"A Christmas Story". I love Ralphie and the gang. I watch it a couple of times thoughout the year as well. I told my son in law he had to watch it BEFORE he could marry my daughter. He had NEVER seen it and they were 29 when they married. Underprivileged kid.. LOL WORSE, his dad was a screenwriter with an Academy Award winning film under his belt.
And others who are top contenders are: White Christmas, It's a Wonderful Life and Miracle on 34th St (1947), There are some really good ones.