While I have lots of favorites, most of my top picks, and the ones I will watch any chance I get, have to do with language, usually in the form of the dialogue. My top #1 favorite is the Zefirelli production of Romeo and Juliet, followed by Casablanca, How Green Was My Valley, Citizen Kane, A Night at the Opera, The Marx Brothers at the Circus, Room Service, and any of Peter Sellers' Clouseau films, especially the one with the dialogue beginning, "Does your dog bite?" which I find uproariously funny although I've seen it 100 times (I have my own copy).