Searching for the Scariest horror movie OF ALL TIME?

I am searching for the scariest horror movie of all time. Ones that will have you screaming in terror. As a child I was scared of stuff like The Grudge and the Ring, but now I find it pretty funny. As for movies like The Shining and the Blair Witch Project. People say its scary, but I haven't watched it yet. Doesn't sound very scary to me. I've also seen Saw movies and they're gory but not scary.