A few weeks ago my wife and I dined at a Napa Valley restaurant and ordered the tasters menu (a different wine w/ each course). One pairing was a German Riesling w/scallops. The wine was the best of the evening.
Since then I have tried several other German Rieslings, from the Mosel-Saar-Ruhr area, these wines were absolutely delicious.
I have long had California Rieslings, but they paled in comparison to the German ones that I had.
The Germans do that very, very well. There is no real competition for that varietal IMO. I have a few bottles of spectacular '76 that are still wonderful. I do not buy by region, I buy by varietal and choose the appropriate region.
The Finger Lakes region of New York also produces some wonderful Rieslings & Gewurtztraminers.