I have tried tons of foods but I have settled on Blue Buffalo for a number of reasons
 
1.  All of my dogs love it
2.  Recommended by Whole Dog Journal -  Iams is not
3.  Does not do animal testing like Iams does (
IamsCruelty.com)  
Here  is another website you also might want to look at:  
The Dog Food Project - How does your Dog Food Brand compare?