If you could only have one book to read, from now onwards, what book would it be, and why?

My first thought was to pick the longest book I know of, which is Harry Potter and the Methods of Rationality by Eliezer Yudkowsky. I think the PDF version is 2000 pages. Not really sure I want to reread it, though. So maybe the book I've reread the most times, which would be 11/22/63 by Stephen King. What a fantastic book.