Hmm, this is a tough question! I'm honestly more interested in what other people will answer - I'm hoping to get recommendations! I find it hard to get scared from horror novels. I guess I just must be a visual person when it comes to horror. But lately I've been trying to find books that will scare me!
I've read The Girl Next Door by Jack Ketchum a couple times. More disturbing and horrifying than straight up horror, I guess. I'm not sure it's explicit enough to count as "gore", but the violence is "on screen" for the most part and just keeps getting more and more, "They won't go there, will they? Oh God, they will... They are." Very suspenseful, even knowing how it ends.
I LOVE Stephen King's The Stand, but it doesn't fit neatly into any one genre imo. It's character drama as much as horror. It's an epic. Now Misery - that scared me! Not the sort of fear that you experience when you shut off the lights for bed, but suspense that is so intense you can't put the book down. His short story Children of the Corn *terrified* me though, enough that I would be closing my eyes and praying to God if I had to go driving down a quiet (as in no one else around) highway past cornfields now!
I recently read Bird Box - if you're a fan of the concept that what our minds imagine when left to run wild is often more terrifying than images put in front of our faces, this novel is great. It's an apocalypse book that takes no time to get right into the 'action' and the characters are forced to navigate the world blind for fear of going mad if they are to accidentally witness the new creatures that inhabit the earth. The paranoia and claustrophobia gripped me.