Aliens
It's actually incredible how the sequel reinvented the formula and continued the fear, suppresion, and power behind the xenomorphs.
The character development is also damn impressive. Hudson died a hero despite crying every chance he got, he showed up when it mattered. Same with Gorman. Vazquez expanded the legacy of what it means to be a strong female character, completely overshadowing Ripley with her pure aggression and spirit. Hicks was the first to take Ripley seriously, and successfully led their escape with Ripleys council. Even Ripley grew and overcame her disparity towards Androids.
The type of movie that reminds you what your standards should be at, regardless of genre. I mean, this is horror/sci fi... not some historical time piece or 2 hour long introspective deep dive on what it means to be a POS table tennis player, no shade.
The cherry on top are the dozens of quotable lines this masterpiece gave us.
Praise James Cameron