4. The Magnificent Seven (1960)
A slightly controversial entry here, given that the film on which The Magnificent Seven is based - Akira Kurosawa's Seven Samurai - is widely considered the pinnacle of Asian cinema. The plot of both movies revolves around a group of men who are tasked with protecting a village and its defenceless denizens. The main difference between the two is that in one movie, it's a group of Samurai (and Kikuchiyo), and in the other, it's cowboys.
Of course, which movie you prefer is a matter of personal taste. For me, music is often a hugely important part of great films, and in my opinion The Magnificent Seven is superior in that regard. Also, I am a fan of Steve McQueen, Eli Wallach and Charles Bronson, so I am swayed in that respect as well. Furthermore, while watching Seven Samurai, I didn't always feel connected to what was going on; whether this was a cultural or cinematic complaint I am still not sure. I am certain of one thing, however: I enjoyed watching The Magnificent Seven more, and that is what counts.