What dog food should i feed my dogs?

There is a brand called "Diamond" which we feed our 16 dogs. It's around $20 or so for a 50lb bag, but i'm not sure if they have it a Petsmart or Petco. Eukanuba use to be a really good, but quite expensive dog food, however i'm sure the price has changed. Just make sure that the food does not have ground corn or soy (especially as the first ingredient).