Not sure if I can manage 20, but, some of my favourites
The Sting
Mississippi burning - probably the most powerful film I've ever seen
Intouchables
Hurt Locker
Dirty Rotten Scoundrels
Let the right one in
Goodfellas
Cinema paradiso
Kentucky fried movie (so quotable!!!)
Anchorman (my dog is named Baxter in homage to this film)