The last 2 weeks, I've read 2.5 books about increasing productivity, at work as well as at home.
First, I read David Allen's Getting Things Done. It's a very practical, to-the-point guide that teaches you some techniques to dramatically improve your productivity. Most techniques and systems are based on common sense and logics. But only if you apply them, you'll see the real value.
The second book I tried to read, was Rosalene Glickman's Optimal thinking. This book is about learning to be your best self. I didn't finish it because it all made too much sense to me. After reading about 100 pages, I realized that I hadn't learned anything new yet. Apparently, my thinking process is very close to optimal, and I don't feel that I need to improve it a lot. If you feel that you're not your best self, and you think you can improve, then this book is probably a step in the right direction.
The third book I read, was Julie Morgenstern's Making work work. Just like Getting Things Done, this book is about improving your productivity. It's not as to-the-point as GTD, but it has more elaborate examples and stories about some of her clients. The 2 books have different approaches and techniques but are built around the same ideas. If you read both books, you'll see some similarities.
If you only have time to read one book, I'd recommend Getting Things Done. I feel it reads faster, it has a more practical format, and it offers slightly better techniques. But if you have more time, I think that reading Making work work is a great supplement, and gives you a different perspective on the issue.