By now you are probably used to the idea that I don't answer any of these questions simply, and favorite book will be no exception. There are a few that mean a lot to me.
Tao Te Ching (daodejing)
No book has ever changed my life more than the ancient work of Lao Tzu (Laozi). A guide to life that is focused not on the reward of heaven or punishment of hell but on achieving balance and wisdom in my life right now. Far less heavy handed than most guides to life, the Tao Te Ching teaches moderation, effective leadership, and appreciation of what you have, lessons that speak to my every day life. It teaches me to be who I am, regardless of who's watching or how I am treated because kindness is from within, not dependent on interactions. Perhaps the most famous quote from Lao Tzu is: a journey of a thousand miles begins with the first step.
Harry Potter: Prisoner of Azkaban
I love the Harry Potter series, and book three has always been my favorite. The twist at the ending of the book truly surprised me the first time I read it, mainly Scabbers being an animagus, and that's pretty rare for me. I really care about the characters in these books when I read them, another thing becoming more and more rare.
If you haven't read Good Omens, you should. It is an amazingly imaginative story with so many levels of cleverness I can't even begin to describe them. This book introduced me to two authors I now easily include on my list of favorites: Neil Gaiman and Terry Pratchett. Very biblically prophetic in nature, this book is thought provoking and timeless to me.
Excuses Be Gone
Animal, Vegetable, Miracle