Germany. He might be able to make it for a cup of coffee in the NBA but no reason for him to, with a great career in the German league and with the Olympic team waiting for him back home. He probably can even make more money in Germany.
He has already stated that he hopes to give the summer league, d league thing a shot, and possibly earn his way onto a roster. Germany will always be there for him.
Giffey is kind of a tweener; not quick enough to play the 3 and not strong enough to play the 4. He will have a nice career in Europe but the NBA is probably unrealistic. Then again I thought the same about Adrian so who knows.