America, by a mile-and-a-half. I'm not even from the states. Norway and the north may be exporting some of the finest extreme metal, but it's all about diversity. Europe has little of that. Over here, you can find quality power metal, death metal, traditional metal, doom metal, and even some good black metal, along with just about every other type. I'm probably going to have a thousand people bitching at me for even thinking that, but the states is the only country that exports every single type of metal. UK being the only exception, no other country can do that.