For me it's either -
The Amityville Horror (1979) or the sequel Amityville 2 The Possesion (1982)
I find I'm more scared of supernatural and physiological films even though being killed by a serial killer is much more likely to happen than being haunted by ghosts or evil spirits.
As the saying goes "it's not the dead you need to be afraid of it's the living."
The last time a movie frightened me was when I went to see A Nightmare on Elm Street (2010). There were so many jump/scream-worthy moments throughout, and the fact that everyone in the theater was just as scared made for an intense environment; however, any time I watch the film now, I question why I was ever scared in the first place
Amytiville 2 is underrated. the guy who gets possessed was a great actor and very scary
to me the scariest move was Child's play because the kids name was Andy and that's my name. Can you imagine hearing a doll saying im going to kill you and your name?