I love them all too but my favourite is "A Spaceman Came Travelling" by Chris DeBurgh.

"Little Drummer Boy" - Michael Jacksons version
"White Christmas" - I don't think anyone can hear that without feeling happy!
"I wish it could be Christmas everyday" - Great song! "It's Chriiiiiiistmaaaaaas"
"Merry Christmas Everybody" - Slade, it's a classic!

"Fairytale of New York" by the Pogues really makes me laugh!

I just bought this really great, 3 disk CD called NOWXMAS and I reccomend it for all Xmas song lovers!!!