What are the scariest horror movies?

I love horror but apparently I don't vibe with a lot of recommendations I find online.

I'd seen so much hype about Event Horizon and I absolutely hated it and didn't find it scary. I just watched Late Night With the Devil and whole it was definitely enjoyable, it wasn't the least but frightening. I also just watched Let the Right One In and really didn't like it. It also was not a horror movie in my opinion.

I will say one of my favorites is Sinister or the first Conjuring. Sinister for the stomach twisting dread and suspence throughout and Conjuring for the same.

So, what movies do you find to be the scariest?