I have read on here that the only premium food that Royal Canin makes is it Sensible Choice line.
Congratulations on making the switch from Iams. It is not a very good food at all. Also, well done on the switch from puppy food to adult. They only need puppy for the first 4 months...if at all.
I would check around for a premium quality food. If you are looking at places such as Petco or Petsmart, you will have trouble finding much. Some chain pet stores carry: Nutro Ultra, Royal Canine Sensible Choice, and Blue Buffalo. Beyond that, the foods they carry are not that great.
Try a local feed store, or go to the websites of some of the premium foods such as Merrick, Canidae, Chicken Soup for the Pet Lovers Soul, Wellness or Innova. They have store finders on their sites and can locate the store closest to you that carries their food!
Good Luck!
Autumn