I guess Battle of the Bulge has always been a favorite of mine because of its drama, great characters, and there's so much going on. Heroes of Telemark is also great. I love all the snowy Norwegian scenery and the story is pretty good too. Oh and Force 10 From Navarone. It's got a nice sense of humor about it I enjoy.
I'll have to watch Where Eagles Dare again one of these days, that was really good too.