Harmonica is THE best role of his entire career. No doubt. But he was really good in "DRUM BEAT", "MACHINE GUN KELLY", "HARD TIMES" and "THE MECHANIC", too. But "ONCE UPON A TIME IN THE WEST" gave Bronson his best role with the best director. So...
I'm not sure that this is the ending. That's the only thing I don't like about "Once Upon A Time In The West":it shows the greatest and most powerful scene 11 minutes before the moment in which it actually ends. So which scene is considered to be the ending scene, the showdown, the "someday" or the goodbye cheyenne (was not in the original version) scene?
Sergio Leone was a Laconic director he didn't use to explain everything.He could end the movie right after the showdown and show all the rest in a 1-minute scene.Anyway I respect every choice he made because He is my favorite director and "Once Upon A Time In The Wes" is my favorite or second favorite movie.
Of course, this kind of ending is the ones you remember the most. But sometimes, "soft endings" can be amazing : remember "ALIENS", "THE MAGNIFICENT SEVEN" or more recently the last episode of "THE SOPRANOS".