To me, the first three films come together as one great film. 'Alien' provides the build-up and foreboding, 'Aliens' provides the climatic action, and 'Alien 3' give us the denouement and conclusion. Each part has its own climaxes, naturally, but I think 'Aliens' gives us the real big one.
And in my personal opinion, 'Alien 3' saved 'Aliens' (Not that 'Aliens' was anything short of near-perfection as it was, but it helped maintain that 100% near-perfection). The second film was ending with something that was to be expected of Cameron- happy makeshift family, mommy, daddy and the little girl, the monsters are dealt and done with resoundingly (Nuclear overkill), and everything's gonna be alright, they're on their way home.
An ending hardly reminiscent to the first film, where the director had originally intended for the alien to win. So, if you consider the beginning of 'Alien 3' to be the next scene in the large movie which, ignoring the credits, takes place minutes thereafter for the viewer, we get a resounding tale of hopelessness, terror, and non-cliché (Hick's face DEMOLISHED, Newt drowned, Ripley chestbursted). The movie ends with the conclusion that, even though Ripley gained the upper hand for a while, she was outdone and destroyed: the only survivor of the first two movies being a cat. The monstrosity has triumphed, it has displayed its deadliness, and the audience can no longer leave the cinema thinking 'Well, the aliens sure got their asses kicked.'
So yeah, the first 3 movies made into one great 'Aliens' movie is what I consider to be the best horror 'movie' ever. I believe A:R is just too far off in the future to be able to have anything to do with the first three films. Hollywood found itself forced to create a fourth movie that had nothing to do with the original three films but for the monsters, characters and lore: no spiritual or fluid continuation, no easy walk over a bridge left by the last film. David Fincher, knowingly or unknowingly, grabbed the 'Aliens' series in its moment of perfection and severed the chain of Hollywood money-whoring before it could truly start by creating a work that allowed absolutely no possible direct sequel... except for maybe A:CM.
Well, there's my personal take on the series.
