This is an old topic, but I was searching for hefeweizen recipes and this also came up, so I thought I would reply. I agree that the German heferweizens that you get over here in the states just don't taste the same as what you get over in Germany on tap. Maybe its the pasturization or just being old. I don't know. That being said, there are a few from the U.S. that are dang good. One of my favorites, Mothership Wit, from New Belgium is no longer in production, though.
1. Sierra Nevada Kellerweis
2. New Belgium Mothership Wit (RIP)
3. Oak Creek Hefeweizen (Sedona, AZ)
4. Schneider Weiss
5. SanTan Hefeweizen (Chandler, AZ)