What I mean is I put several of those tracks in a whole other tier of really iconic movie themes and such that are just incomparable. I feel it's unfair to pit any score - including all the Alien ones - against stuff like that, in terms of how it rates. That's an exercise in self-fulfilling prophecy, IMO.
I also feel that those films are really a whole different animal from the Alien films. Leone's films have their own thematic underpinnings and these vast, operatic scores; Jaws is a big high adventure monster movie; Conan is another big epic thing, and Star Trek is this sweeping brand unto itself. Alien and the subsequent films are these dark, creepy suspense pictures - it's just a different breed, I feel. And I think the Prometheus score is doing its own thing, too, different from what came before. But just because something is not John Williams or Jerry Goldsmith's finest works doesn't mean I don't think it can rate. I always found Howard Shore's score for Seven to be excellent, but I would not try to match it up against Jaws, Conan or Trek - it's something totally different. Perhaps not as instantly memorable, but it works for me.