I'm a big fan of TimeOut guides. They just cover individual cities (and surrounding regions) but I find them most suited to my travel needs - covering touristy stuff, off-the-beaten-path stuff, dining, shopping, and a good focus on nightlife and bars
They also have all the historical and cultural context like all the other books, but I think they do the best job of covering everything a city has to offer in one place.
As for books by country, so far I've liked Lonely Planet.
I recently read a great guide comparing all the different travel book series, who they appeal to, what they cover, how much of a tourist they make you look like, but I can't remember where!