Yeah yeah, this may be a controversial statement, but I would love NOTHING MORE than to be proven wrong.

I genuinely believe that there's no good horror anime out there. Something that actually gives you chills and makes you Avert your eyes from the screen just doesn't exist. Junji ito is creepy and gross, sure, but I wouldn't say it does enough to be considered proper horror

Other horror animes just have a creepy aesthetic or rely on dark story beats like shiki or another. I don't know if it's just the disconnect from being animated in the first place, but I don't think anime is capable of delivering a true horror experience.

Please, if you disagree, prove me wrong, I need to be wrong about this

Not what you're looking for, but I think Shinsekai Yori and Made in Abyss have pretty impactful psychological horror elements. I haven't gotten around to watching Higuarashi, but it's well known as a (apparently psychological) horror anime.

I do agree that the medium limits the visceral impact that visual elements have. Despite that, I was still fairly grossed out by some select scenes in Orb: On the Movements of the Earth.

Also, if you want something like a horror movie, you probably want a movie... The same suspense can't be sustained over separate 20 minute chunks.

Movie or not, I don't think there are many anime that are even attempting to fulfill your horror desires.