Without looking at the list I thought Alien should be number one. The Day the Earth Stood Still should be in the top 10.
A now dead thread, but if I may comment: The Day the Earth Stood Still is a classic, pacifist scifi film in an cold-war era when pacifism was not politically correct (thus it is scifi), and absent the obligatory sensuality - aside from very brief semi-private kissing btwn fiancees - as well as vulgarity and profanity that flows from "Hollywood."
But a critical analysis is that, as is typical with sci-fi films, many avoidable absurdities are evident.
1. Advanced race on a mission makes no attempt at communication as to its purpose before hand, even in the age of radio and TV.
2. Advanced race knows little about humans, except their violent nature, and cares not about that except that it somehow is now a threat to the universe, even though a few robots could neutralize anything coming from earth.
3. While attesting to the violent nature of humans, and with no prior communication, alien craft and lands in DC. and the first attempt at contact with humans by this alien, "Klatu," is in a suit for no reason, and who directly walks up to an armed soldier, then triggers a small gun-type device, as if ignorant of the expected response.
4. Slow moving Gort, at about 9', then appears after Klattu is shot, and its weapon is a single or forked beam that that takes about 6 seconds to warm up and heats or vaporizes weapons, and yet it receives no response by artillery before they are vaporized.
5. Unlike in the second instance of being shot, Gort does not retrieve the alien.
6. No pictures are taken of the alien while in custody, thus he can later roam the city..
7. Klatu requires a world meeting of all leaders, yet is so ignorant that he expects this would be no problem, despite the fact that and so the earth must be reduced to as burned out crisp unless they submit to be governed by robots who are intolerant of any sign of aggression, or otherwise irresponsible behavior, and only understands alien speech.
8. Advanced race alien cannot communicate with Gort, except verbally or by flashlight, which the alien must borrow from a child!
9. Gort and craft is only guarded by 2 soldiers, and later is able to go all the way to a police station and retrieve the body of Klattu.
10. Klattu carelessly trades alien diamonds for $2, and leaves one on the carpet of his rented apt., to be picked up by unworthy boyfriend, leading to manhunt.
11. Without communication, Klatu has no idea what Gort, the destroyer of worlds, would do.
12. Final and only speech by Klattu is a threat, and awaits a response, without saying how, except it seems that of disarmament.
13. If the aliens were so advanced, they would know that being ruled by robots would result in unity, that of every race seeking to find a way to circumvent this unfeeling. unfeeling, unrelation-able, unmerciful police-god, who deals with aggression (at the first sign of which), or otherwise irresponsible behavior.
14. Klattu does state that the power to give life is reserved to the Almighty Spirit. Yet the True God, as the author of life and of all good things and good laws, is that which mankind has been rebelling against from the beginning, despite Him being expressive and communicative, sacrificially merciful yet with justice toward the impenitent. Whose program of revelatory testing (thus enabling man to be able to make consequential choices) will result in a world of peace with freedom, inhabited by souls who love Him and all that He is, and who will not sin even if able, since they strove against it in this world of testing. Glory to Him.