Personally I'm not a huge horror fan but I like the first Scream and the first Alien is one of the best movies ever made.
Most Helpful Girl
The Paranormal Activity films. That stuff creeps me out more than blood and gore. The Strangers is good. A Quiet Place freaked me out too.1
Most Helpful Guy
Friday the 13th, The Haunting, and Nightmare on Elm Street1