I was reading the thread about The Hills Have Eyes and i thought i should definetly see that! (btw we are talking about the new version of that movie, because there are two arent there?)
Anyway, i like horror movies, even pretty ****ty ones cause im easy to scare...
But of course good ones are always better, the ones that really haunt you!
I would recommend these:
The Tale Of Two Sisters (really weird, it made me all confused, very twisted)
The Last Horror Movie (ok it isnt traditional horror really, and the name is a joke you have to see the film to get it

)
The Cube (maybe not horror actually, but a classic)
Dark Water (original, i know little ghost girl is a huge cliché but i like this one more that The Ring fo example)