What a great topic!
I'm going to have to say...most hated book of all time: The Kite Runner.
This book was required reading during my senior year of high school for all non-AP Literature students. I was in AP, so wasn't required to read it (originally), but at the end of the year, my teacher decided to make us read it. It was the kind of book that all the non-readers LOVED (possibly because of it's simplicity and lack of literary devices, and the fact that it used the 'c-word')...but to me it just seemed like an interesting story happened to a guy, and he wrote it down. VERY irritating to read for me. All the way through the book I kept thinking "this would probably make a better movie..."
Unfortunately, by the end of it, I was SO sick of the entire concept that I couldn't bring myself to see the movie. I wonder if it was any better...