The best food is the one that your pet does best on. Some dogs do not do well on the premium foods - my own dog had terrible diarrhea with Eagle pack, and Solid Gold gave her IMMENSE feces.
Look for a dry kibble with a named protein source (ie Lamb or chicken, NOT "meat") as the first ingredient. After that, it gets complicated... many kibble companies will split ingredients, so that a food that is mostly grain still looks good: Ie. Lamb, rice flour, brewers rice, rice bran - chances are good all those rice ingredients together will outweigh the lamb. So look for more than one meat ingredient.
Avoid artificial colours and flavours - your dog doesn't need them
Avoid preservatives like ethoxyquin, BHA and BHT
Here is a good website where you can compare ingredient lists:
http://www.doberdogs.com/menu.html