For me it was Gerald’s Game by Stephen King. I think it’s a fantastic novel with amazing character development. The main character is extremely realistic and well written. Despite the seemingly silly premise, I was invested throughout the entire thing. The main character’s development is really what sells it for me.
That being said, I am absolutely not reading it again anytime soon. There are two scenes in particular(if you’ve the book I’m sure you know) that managed to make extremely uncomfortable, mortified, and disgusted. My biggest fear is being trapped and helpless, so this book really got to me. Fantastic book, I’m never picking it up again.
Either that or Lord of the Flies… Dear God.
A Song of Ice and Fire books. I loved it. Finished the last book in 2011? I think. Waited for book 6 for a while, finally gave up. They weee very good but at this point I have forgotten most of the story and characters and even in the off chance Martin finished that series, I couldn’t bring myself to reread that gargantuan series just so I could remember everything before continuing.