some people like Blanchard's because it is more organized in their models. Starting from Keynes short run, to medium run and then long run. There are more math equations in the first part than Mankiw's. I use it for the senior undergraduate's class. it is too simple for phd, but a little bit too much math for undergraduate intro class. The biggest problem is the book did not include some hot topic in recent policy debate. and some kind of messy in the second part (e.g. the open economy).