Probably The Third Man. It has an outstanding cinematography and acting. But in terms of story it offers nothing exciting or new to offer. I mean the dialogue is fine and everything but the story was average with its typical twists and a run of the mill final chase scene.
I've actually only seen 31 of these films. This would be a good challenge for me (to watch all of these other films). The list- Man On Wire, toy story, toy story 2, wizard of oz, godfather, citizen kane, rear window, dr. strangelove, north by northwest, the third man, all about eve, laura, seven samurai, modern times, the 400 blows, on the waterfront, aliens, chinatown, rahomon, singin in the rain, cool hand luke, the terminator, maltese falcon, rebecca,, 12 angry men, treasure of cierra madre, city lights, jaws, grapes of wrath, anatomy of a murder, the gold rush.
BQ: I can't really form an opinion because I have not seen most of the list, there's a lot of foreign films I'll say (not that anything is wrong with that), but of the ones that I have seen, not one is genuinely bad.
BQ2: I would save Aliens, because it is my 2nd favorite movie. (Terminator 2 has 98%, grrrrr......)