1.) Once Upon A Time In The West
2.) The Good, The Bad & The Ugly
3.) For A Few Dollars More
4.) Outlaw Joesy Whales
5.) Unforgiven
It's a very Eastwood centered list but what can I say, he is in the greatest Western movies ever made, imho. Plus, I simply prefer Leone over Ford. This list might change as there are still many classic Western I haven't watched yet.