You really expect anything to come out of this?
I mean, it's just people's opinions!
I obviously voted for Alien

.
Let me give it's merits.
-Great visual design, the ship felt like a futuristic freighter, it felt real, not like a glorified space station or such.
-Believable monster, not some evil creature intent on the annihilation of others, but an unexplained organism, motives unclear.
-Wealth of characters, unlike NOTD each character is extremely personalized, each is obviously different, and all of them react differently to the situation.
-Pace, by the end of Alien, the suspense was almost unbearable, just watching the film, expecting the Alien at every turn, it becomes unsetteling.
-A creature that can keep up with you, unlike NOTD, he isn't a shambling dead thing, it's a living breathing thing, quicker, stronger, and much more agile, it brings up a sense of dread, you can't escape it at all.
-Chest-burster! Face hugger!
-Ridley Scott as director, I mean cmon, is there a better director? Gladiator?
-Great atmosphere, NOTD felt dry, I liked Alien's creepy, quiet, and strange surroundings.