We are in the process of switching foods right now. We previously gave them Eukanuba and they've done great.
My main reasons for switching...I got a free 6lb bag from the company & the dogs loved it, plus...the smell. It actually smells good (not good enough for me to eat but good), much better than the Eukanuba does, and the ingredients are better.
But everyone has their own thoughts on the subject.
Here is another thread if your interested:
What's the best kind of dog food?
And here is a link to help aid in the selection of Pet Food
Selecting a Commercial Pet Food