I'm probably going to be the black sheep in the Alien community for saying this, but here goes.
After watching Alien and Aliens back-to-back last night (on the big screen!), I can say that Alien is, by far, a superior film to Aliens. It has better acting (which isn't saying much given that both films are very well acted, but Alien feels more real), a more creative set design (the derelict), the Alien actually felt, y'know, *alien* (as opposed to the generic space bug of Cameron's film), a much more unsettling and scarier feel to the whole package (rather than the run n' gun of Aliens), and the characters didn't irritate me like some did in Aliens.
Sorry folks but Hudson really started to irritate the f**k out of me by the time the APC was trashed and f**k NEWT. Holy shit. I wanted that Warrior that corners her in the water to kill her, if it meant not having to endure her ear-piercing screeching anymore.