Uh oh - asking about American barbecue sauce is opening a HUGE kettle of worms - it deserves its own thread. It falls into a couple of categories: what meat are you discussing and how was it cooked, and what sauce are you serving with it (or marinating in).

Charles Kuralt, the late CBS news moderator/travel reporter had an essay about North Carolina BBQ that compared it to other types around the US, and while it may not be lost forever, I can't find it at the moment. It is a short but seminal study of the state of smoked/grilled meat in the United States.