I can't think of many...
>The Shining
>Alien
>Black Swan (is that even horror?)
I enjoy schlocky monster/slasher/ghost movies too but for different reasons. Just seems like there's not a lot of movies out there that make me think while making me scared at the same time. Many good horror films succeed in making the audience terrified but aren't really saying anything.
>watch xenomorph bite trough someone's skull
>really makes you think
Anyways, i think i know what you want:
The Void (2017)
Dark Song (not particulary scary, but very /x/ tier concerning the occultism)