Elf is #1 for me, no doubt about it. After that I don't really have an order.
A Christmas Story to me isn't the be-all end-all Christmas flick that people make it out to be, but it's still great so it's on the list for sure.
Then I'd also have to include Christmas Vacation, Die Hard, Home Alone, Scrooged, Love Actually (sorry about it) & A Nightmare Before Christmas.
I don't think it's considered a movie but I loved Mickey's Christmas Carol as a kid so it still holds a special place in my heart this time of year too.
Crap that's more than 5.