Hard to chose just one. If it had to be one then it would probably be Shawshank Redemption.
Other favourites include Raging Bull, Godfather, Reservoir Dogs, GoodFellas, Bullitt, Black Hawk Down, Apocalypse Now, The Deer Hunter, Great Escape, Bridge On The River Kwai, Mad Max, Kill Bill I and II, The Bourne Trilogy, and Pulp Fiction. Others include Gladiator, Cinderella Man, Memphis Belle, Mr. Brooks, Juno, August Rush, Field of Dreams, Romancing the Stone, Vitus, Wall-E, Happy Feet, and Finding Nemo. Sports movies like The Natural, Hoop Dreams and Touching the Void. Docos such as March of the Penguins, Winged Migration, Microcosmos, Man on Wire, and of course This is Spinal Tap. And finally comedies: The Castle, Death at a Funeral, Monty Python's Holy Grail, Billy Elliot, The Full Monty, Four Weddings and a Funeral, Little Miss Sunshine, Fargo, and Happy Gilmore.
As you can tell, I like watching movies!
"If you're going through hell, keep going." - Winston Churchill