Once Upon a Time in America for me, one of my all-time favourite films. But his others are all cracking films too. Next favourites would be Once Upon a Time in the West and The Good, The Bad, and The Ugly.
Incidentally, Sergio Leone was the one of the first people that Ruggero Deodato showed Cannibal Holocaust to. Leone told him it was a masterpiece, but that he would get in a lot of trouble over it. No shit.
