1. Once Upon a Time in America (the greatest movie I've seen, not my favorite)

2. Goodfellas (my favorite movie)

3. The Departed

4. Godfather I & II (I won't separate them)

5. Jackie Brown/Se7en (Can't decide!)

Pulp Fiction would be next

If the Big Lebowski counts, it becomes #5 lol. Hilarious.

Close (no order): A Bronx Tale, American Gangster, Training Day, Heat, Reservoir Dogs, Fargo, American Psycho, Raging Bull, Casino, Donnie Brasco, Carlito's Way (underrated), Scarface, North by Northwest, The Insider, and if war movies count: Apocalypse Now & Full Metal Jacket.