I'll take a stab at this. You can find a good food at most pet stores, but not most grocery stores, at least in Boston. Real good food is pricey, but generally speaking you feed them less than the crap food. Look for a meat (chicken, lamb, beef, whatever) as the first ingredient rather than corn. There are people who feed raw, and I've heard good things about that, but I don't know enough to really give any info about it. German shephards might do well with that. From my own experience, I think finding a good food and being consistent is probably best, otherwise their stomachs may suffer. I think this forum has a sticky called Wiley's Food grading or something that someone posted with a ton of great information on dog food.