I do not recommend Iams when asked for my opinion - I prefer foods with no by-products.
Unlike some, I find Nutro - especially the Nutro Natural Choice Complete Care line, to be one of the better quality foods on the market for the price. Is there better - yes, and it's more expensive. Depending on your wallet, look for foods that do NOT contain: by-products, by-product meal, animal or poultry digest, corn gluten meal as the only source of protein, corn - in cracked, whole, meal or grits form (corn gluten meal is a source of protein and not as likely to cause an issue with a kitty who reacts to corn, however many prefer to feed a food w/out corn gluten meal), soy or wheat, multiple grains in one food.
I prefer my dry foods to be preserved w/out BHA/BHT, to have meat(beef or lamb, venison what have you) or poultry/turkey or the meal of these, listed as the first ingredient.
Brands that I consider worth looking at - Nutro Natural, Innova, Innova EVO, California Natural Chicken and Rice, Natural Balance and their Venison and Green Pea (also available in canned), Chicken Soup for the Cat Lovers Soul, PetGuard and Felidae.
hth a bit,