Peanut had soft or runny poop when we had her on Nutro adult food. We switched her to Wellness and that was better but ever since she has been on Blue Buffalo Chicken and Brown rice she has only been runny when she has 'excita-poo' from playing too hard or with her puppy friends when she hasn't seen them in a while. Or on long car rides.
I thought about switching her to grain free, but she is doing so well on her current food... plus any time she has had a rawhide or bully stick she gets the soft stinky poops! So, she doesn't get anything like that anymore.