I love the dollars trilogy. But I still think the best is Once Upon A Time In The West. There's no Eastwood or Van Cleef, but Bronson and Fonda are superb.
The Django films are worth a look too.
The Black actor, Woody Strode, was one of the first two Blacks to play in the NFL in the late 1940's. The blonde headed actor, Al Mulock, committed suicide during filming. He jumped out of an upper level window in full Western garb.
The 'Mare's Leg', the shortened lever action that Strode used in the scene always fascinated me.
Interesting trivia on Al Mulock
http://cscottrollins.blogspot.co.uk/2012/07/good-bad-and-ugly-bizarre-death-of-al.html