I've used IAMS dog food for over ten years now and am a loyal fan.  I've used the different formulas for different dogs with the same good results.  My original vet (now retired) recommended it to me and I've bought it ever since.

Even the rescued dogs I've had eat this (when who knows what or when they ate last) with no difficulties.  It's expensive compared to other foods, but its quality is worth it.  The doggies stools really are smaller, too:  a bonus when you have more than one pup!