Didn't Michael Jackson in his later years start to claim that the USA is the best country in the world to be a beer drinker? It certainly leads the way in a range of more modern styles and I have found there they have the passion, inventiveness and inquisitiveness there to really try to push the boundaries and both in terms of developing new styles and refining and shaping existing ones.
But for me, of all the countries I have visited, the one which takes its beer the most seriously, the one that really elevates it into a cultural staple above all others is Belgium. They have a wide range of styles, of course, but they really excel, in my opinion, at making the really complex beers both well but also consistently. Brewing there is taken so seriously it's almost a religion. It may not be the most innovative modern brewing country but I think it's the country which cares most about beer. The beer lists in cafes, bars and restaurants all over the country read like wine lists do in other parts of the world. Whether it makes the best beer in the world is up for debate (although I think it does) but I think its beer culture helps it take top spot as far as I'm concerned :)
EDIT: I saw bantu1957's comment about Poland and it made me check the poll again. There is an argument for Estonia as a contender. They have an ancient and, in some pockets, continuing tradition of farmhouse brewing and their craft beer scene is spectacular. They might have the greatest number of excellent beers per capita of anywhere in the world!