I think the one reason that Taxi Driver has any pull here is its hype. Its a Martin Scorsese movie starring a very young Robert Di Nero, Jodie Foster, and a few others on their way up. But overall, it is not the best movie in any light. The story isn't the best, the movie can be boring, and the climax is killed in it. On the other hand, Alien is a revolutionary movie. A science fiction movie, that good, that long ago is incredible. No one had seen anything that realistic. It is highlighted by Weavers impressive lead in the film, that is one of the best I have seen from a leading actress until Terminator a few years later. Vote for a movie you wouldn't watch twice, or vote for the clearly better movie, Alien.