Wonderful thread, reading through now but wanted to add mine (before I get too sidetracked ordering all of yours...) I tend to track down and reread those that stay with me 
Black Harvest by Ann Pilling. Family go on holiday to Ireland and tap into the past of the potato famine. Children’s horror, but I still reread it. Never forgotten the feelings it evoked.
Stephen King, The Stand. Over wordy, jumps between narrators and definitely needed a reread when I was a little older but the portrayal of a world and human behaviour post-viral apocalypse has always stayed with me.
Stephen King, Insomnia. The description of the soul-wearying curse of insomnia and how it seeps into every aspect of your life was exactly what I was experiencing, put so clearly it made me want to weep. Bloody good story too!
Dan Simmons, The Terror. Fictional account of Franklin’s expedition for the North-West passage. Well researched with excellent detail. Vilified certain characters unfortunately, and ending is debatable, but kept me gripped and inspired lifelong interest in arctic exploration. Longing for a decent full audiobook!
Stephen King (as Richard Bachman) The Long Walk. On multiple rereads it’s got holes, but grips me enough to forget them every time. Still remember the first time I read it, many years ago.
Robert C O’Brian (sp?) The Silver Crown.
The Bewitching of Alison Albright (sp?)
The Girl in the Blue Velvet Dress.
I barely remembered the last three, just the names and the effect they had on me. Found the first two recently and they did not disappoint!
Still hunting for the third, also a book where some children were going on a visit but got snowed in in a strange (?) house, and made turnip or swede soup... and Ghost Ship to Ganymede (sp?)
Sorry, that was long 