Pfffft, you looked over Starship Troopers or the two original Alien flicks for this? C'mon.... 
Starship Troopers is very good, but I think Total Recall has a much better plot, and better performances. Mind you, Starship Troopers has some of the satirical bits that made Robocop so good, but I'm rating on a scifi scale, not a satirical cleverness scale.
Alien is a good movie, but it's a suspense movie that happens to take place in space. Total Recall is a flat out science fiction movie. It's very good, and it uses the scifi setting for maximum effectiveness, but labeling it as scifi would be like calling Apocalypse Now a vietnam movie.
Aliens is a shitty action movie so it's eliminated from the running.