http://www.amazon.com/Radicalism-American-Revolution-Gordon-Wood/dp/0679736883

The Radicalism of the American revolution would be my pick. From the Amazon blurb:

In a grand and immemsely readable synthesis of historical, political, cultural, and economic analysis, a prize-winning historian depicts much more than a break with England. He gives readers a revolution that transformed an almost feudal society into a democratic one, whose emerging realities sometimes baffled and disappointed its founding fathers.

This book really does a great job explaining why the Reovolution was such a singularity moment in world history, and how the ramifications of the revolution transformed not only America, but also Europe and eventually the world.