"Fistful of Dollars" or "Outlaw Josey Wales" easily for me. Or any of his WW2 roles.
Josey Wales is a good movie but it's also evil, because it whitewashes Quantrill's Raiders.
The romanticization of what was basically the Confederate branch of Al Queda is abhorrent, since their origin in bloody Kansas stemmed from the desire to turn Kansas into a slave state, and in Missouri, to overturn the majority's decision to stay in the Union. This was NOT about states' rights, but slavery - though once the killing started, of course, things got muddled.
It would be like making a movie about a German in Poland who engages in guerilla warfare to help the Nazis because he wants the Sudentenland to become part of the Reich. Making him the hero of a movie would disgust us, same attitude applies to Confederate bushwackers.