I used to feed Solid Gold to my dogs for years and just recently switched to Timberwolf due to the fact that I think they were getting tired of the same stuff. And its hard for me to find out where I am but easy to find the Timberwolf. But I believe all are good foods, I just only have experience with the Solid Gold. I fed the Millenia & the Hund N Flockn. Tried Barking at the Moon for a few months and my boys did horribly on it and gained about 5 pounds each after 2 months of eating it. Its very high in protein and pretty decent amount of fat too, and high in calories. Not saying my dogs case is for all dogs, my dogs just did not do well on the BATM but did fine on the other types of Solid Gold.
Good Luck!