I guess it depends on the age you were when you saw it...but, I know "IT" scared the hell out of me when I was a kid. I still hate clowns to this day
The Decent
So the Exorcist wasnt anyones scariest?
Gonna go old school and say the original Excorcist.
The Ring scared the piss outta me. 2nd one wasn't much better. The Omen (new one)was pretty freaky as well.
I haven't really watched any older ones, but I'm sure IT would scare me as well.
Oh, and I refuse to watch any spider movies because I'll likely never sleep again.