Man...I'll probably get reamed for this, but I watched blair witch project again recently, in the dark, and what it lacked in gore and "gotcha" moments it made up for overwhelmingly in creepiness and leaving one feeling completely unsettled by "unknown/unseen" factors. That freaking last scene...even thinking about it again makes me shudder.
Oddly enough, I just checked on IMDB and it turns out that they are remaking "Night of the Demons." Can't help but wonder if they will have the "lipstick scene."
Are you looking for something suspenseful or something gory? Films from Dario Argento are spooky if you can get into the quirky, baroque sets, first person viewpoints, and stylized violence. Many American horror classics such as "Friday the 13th", "Halloween", and "A Nightmare on Elm Street" are essentially lesser mimicries of Argento's style.
His closest approximation to "The Exorcist" would be "Susperia" if you like occult thrillers.
I always thought "Angel Heart" was an underappreciated horror film. Roman Polanski made some excellent horror films back in the day. His most recent I think was "The Ninth Gate", but that was pretty weak in my opinion. His best known horror film is "Rosemary's Baby", which I thought was excellent, as were "Repulsion" and a very similar film he made called "The Tenant".