This is a really tough one but I would have to say the UK, but only because they invented Heavy Metal, Punk, Goth and Jungle. The US is a very close second for inventing Hip Hop, House, Techno and more recently Witch house.

Had to go UK

I originally voted UK, but I think now I prefer the music of the US. Both have quite a bit of diversity in their mix, but since the US is larger it has the potential to be greater in that aspect. Difficult decision because of the number of great bands in the UK but the US came up with jazz, hip hop, blues, psychedelic music, as well as the great classical movements that came about in the US (though a lot of my favourites of American classical music was paralleled in the UK).

1. Germany
2. UK
3. Italy
4. Austria
5. US

Germany, Italy and Austria are not in the anglosphere.

Ah, for some reason I thought that meant 'Western' countries. If it's limited to English speaking ones then who cares.

Tie between UK and US for me . . . which is remarkable for the UK, given that it's the size of a single US state and it only has about a sixth of the US population.

The Netherlands, obviously, becayse it's my country. (I actually only listen to like, 3 Dutch artists but shhh about that)

America, UK, and Australia.

United States > United Kingdom > Australia > Canada

Canadia sucks because Qwertyy.