For a movie to hold my attention, it needs compelling vibes and atmosphere. The plot can be paper-thin as long as the vibes are right. I actually prefer paper-thin plots, since I’m honestly quite dumb, so if the plot is too complicated I get lost and lose interest (for example, I’ve tried watching The Lord of the Rings many times but haven’t been able to get through it for this reason), lmao. That’s why my favorite kind of horror is folk, atmospheric horror: Suspiria, The Witch, Midsommar, Hereditary, The Wicker Man, Blink Twice, Hagazussa, Lamb, The Blair Witch Project, Rosemary’s Baby…
Horror movies, at their core, are about subverting expectations. You cite “Suspiria” and “Midsommar” as favorite movies. The second and third acts of both movies are a massive subversion of audience expectations. And the best horror movies can most jarringly break what viewers anticipate, all without using jump scares.