Bayern M.
Is any other country's team selected so heavily from one club? I can't think of one.
Spain at their best was basically Barca and a few Madrid players.
And that's a big reason why we were so successful, imho. Del Bosque has got a lot of criticism for keeping the same core throughout the current cycle, but doing so is what won us the cups, imho.
In international footie, team cohesiveness >>>>>>>> everything.