When pressed to talk about a non-fiction book, only one book really comes to mind. The Tao Te Ching is a book that has changed my life in ways I couldn't even imagine. I don't really care about what translation you are talking about, because each interpretation brings new life and meaning to this profound wisdom. Unlike many, I don't judge any one translation as better or worse than others, I view them as merely serving a different purpose.
I never had a Taoist teacher, hence why I don't understand the many nuances of the tradition steeped practices of many who consider themselves true Daoists. I'm not familiar with all of the many sects that have formed, and all of the rituals associated with it. But that's okay with me. The book is what called me, not the religion. The book that lays out a blueprint of becoming a sage.
For me, this blueprint leads to happiness and inner peace, and that is what does matter to me. I've been called "new age" or "fringe" by many of these other Daoists. That's okay with me. Those are merely labels and do not define me in any way. I must follow my path, and they theirs. I will learn what I can from them, and hope that they may learn a little from me as well, even if that is just tolerance.
The Tao Te Ching speaks to me, no matter which translation I am reading.