This depends on what country traffic you want? Say, you want only Japanese traffic because you run a sick manga site and you want to sell real dolls to Japanese wankers. In this case the only country you should have in Good group is Japan. Also keep in mind that ad server companies will reward you for traffic from Good countries whose traffic converts, so they are likely to buy something after clicking the ad, such countries as Germany, etc.... Chinese will typically buy nothing ... ;-)
