I think mine’s Z for Zachariah. The book is insane. A psychological survivalist thriller between a 14 year old girl and a strange man with unknown intent. The movie is… not this. They changed everything meaningful about the characters and lost all the tension. Hope someone does it properly one day. What’s your adaptation peeve?
Anything Resident Evil by Paul WS Anderson. With that, it’s like the game franchise is cursed to never have a good live action adaptation.