I have my opinions on the perfect minimal essentials, but i'm not expert. Stagecoach is the pinnacle of the old hollywood style. The Searchers is maybe the best ever and shows the trending tonal shift toward grey anti-heroes. (really The Searchers is a stepping stone toward the anti-heroes in The Godfather). that's your american westerns. Stagecoach and The Searchers, specifically how they contrast. then 2 italian westerns. the Good the Bad and the Ugly because its the absolutely most iconic. and Once Upon a Time in the West because the filmmaking chops are arguably better and the story is more orthodox and less like a tarantino movie.
imo, those 4 movies are enough to understand westerns in the context of film. and if you want to see the evolution, the best neo-western i think is No Country for Old Men
