Which ones do you rate ? For me I'd say: Inside Hostel Evil Dead Hills Have Eyes Wrong Turn 2 Midnight Meat Train Halloween High Tension Others will come to mind.
I find straight up horror movies to be usually shitty. I liked Alien(s) - Action/SciFi/Horror Army of Darkness - Comedy/Horror The Thing - Kurt Russell/Horror Jaws(?)
Scream is put as thriller/horror, and is a favourite of mine, but not really for the 'horror' component.
Saw springs to mind, not the endless sequels though. Silence of the Lambs another, although it's more thriller than horror.
Midnight Meat Train is one of the worst films I've ever seen. One of the most laughably ridiculously terrible "twist" endings too.
Besides a few of the ones already mentioned like, Alien/Aliens, Halloween, Jaws, Evil Dead films... I'd go: The Shining, The Birds, The Exorcist, Psycho, Poltergeist, Event Horizon Contemporary: The Ring, 28 Days/Weeks Later, The Others Foreign: The Devil's Backbone, The Orphanage, Ringu, Audition, Rec
Of those I think The Shining and The Exorcist are pretty good. I actually liked Paranormal Activity as well.
Saw some pretty good french movie. It was about these 2 birds getting hunted down by some killer, and it turned out one of the girls was the killer.