I know they get slack for not being "scary enough" but I absolutely adore the Predator movies. my recent favorites have been Predator 2 (1990), AvP (2004), and Prey (2022). I love seeing how the Yautja have gone from a simple movie monster to a fully fleshed out alien species, as I especially loved when we got a view of their homeworld in the beginning of AvP:Requiem (albeit the rest of the movie kind of sucked, Rip Scar and Wolf).
But as for more traditional horror movies, nothing can outdo the original Scream and Alien movies. Scream is my perfect "sit back and watch the bloodbath" movie, while Alien always keeps me tense and worrying if Ridley and Jonesy would escape this time (even though I've already seen it a bajillion times)