That's kinda tough to say...It depends on what you're "in to"(ie:scares you)...Slashers? Demons? Spirits/Hauntings? Monsters? Aliens?
For example...I was telling my nephew how the Exorcist was the scariest movie ever made....One day I decided to play it for him so he'd be able to tell others he'd seen "the best"...Turns out the kid didn't even jump or turn his head during the whole thing...Told me afterwards that it was "OK" but didn't really scare him that much....
Damned video games!...Got the kids all numb to horror...