Aliens may be my most-watched film. It's my go-to choice for a lazy/hungover Saturday afternoon. In the way it builds up to the chaotic, shocking scene where the marines get their asses handed to them, and then becomes a one-against-many defend the fort movie - it's the perfectly structured and paced action film. And it still looks great.
But I agree with Toby that Alien is on a different level artistically. Superbly atmospheric, from the soft lighting to the spare, eerie score, to the camera tracking down the oppressive tunnels and hatchways of the Nostroma. Every shot framed perfectly. Alien could have been made by Kubrick. And there hasn't been anything like it made since. It's imitators are too gory, or too action-oriented, or the characters are a bunch of hot 20-somethings and cliches. Nothing else captures the mix of realism, strangeness, and horror of Alien.
But I agree with Toby that Alien is on a different level artistically. Superbly atmospheric, from the soft lighting to the spare, eerie score, to the camera tracking down the oppressive tunnels and hatchways of the Nostroma. Every shot framed perfectly. Alien could have been made by Kubrick. And there hasn't been anything like it made since. It's imitators are too gory, or too action-oriented, or the characters are a bunch of hot 20-somethings and cliches. Nothing else captures the mix of realism, strangeness, and horror of Alien.