Picking the book I am most grateful for is pretty hard; there are so many great books out there. But ultimately it has to be Harry Potter (I know that's actually 7 books but whatever). People might say that's an obvious choice because of it's so acclaimed but really, when was the last time you read the first HP? There is a reason why everyone loves it. I read HP probably once a year and every time I read them they are still amazing. J.K. really knows how to entice the reader. And she has such great little details, like how Dumbledore loves lemon drops; it really gives it a fantastic feel.
And she does this in. every. scene. ohemgee. Really when I reread this book for like the 15 millionth time, I was still blown away. And this is just the first book! It gets better with everyone.
I'm grateful for HP because it shows me how clever a book really can be and a fantasy one at that! It's even a THEME park now. Wow. Just wow.