After you pick a few to choose from you could look them up on this list just to see what they have to say about it(looks like it hasn't been updated to include some manufacturers' fairly recent ingredient changes though):
Best 5-Star Dry Puppy Foods
Also, if you are unaware of "ingredient splitting", I highly recommend this only so you are aware of it when reading ingredient labels:
Ingredient Splitting - The Pet Food Industry's Dirty Little Secret