I would suggest visiting the follwing site for links to helpful info on your quest to find the non-existant perfect diet:
http://www.consumersearch.com/www/fa...d/reviews.html
It will link you to some sites (dogfoodanalysis.com, animalark.com, dogaware.com fo name a few) that have compared various dog (and cat) foods, examined the companies that produce them and give you a brief overview of what you should know when searching for a commerical food. The links also examine raw and homecooked diets as well.
Important to keep in mind though, the information on all of the sites are based on the opinions of the site editors, so take that for what it's worth. Many of them are also very one sided. They do however, mention publications that you could track down for even more info.