Agree. I would never feed either. Jackson eats Orijen and Acana kibble, and we usually get NV Instinct canned food or Go! Endurance canned food to mix in.
To me, it seems obvious when you really compare the ingredients between Orijen and Iams for example. Look at all the meat and fresh ingredients!
IAMS: Chicken, Corn Meal, Chicken By-Product Meal, Ground Whole Grain Sorghum, Chicken Fat (preserved with mixed Tocopherols, a source of Vitamin E), Dried Beet Pulp, Chicken Flavor, Fish Oil (preserved with mixed Tocopherols, a source of Vitamin E), Dried Egg Product, Brewers Dried Yeast, Potassium Chloride, Salt, Caramel, Choline Chloride, Minerals ((Ferrous Sulfate, Zinc Oxide, Manganese Sulfate, Copper Sulfate, Manganous Oxide, Potassium Iodide, Cobalt Carbonate), Vitamins (Vitamin E Supplement, Ascorbic Acid, Vitamin A Acetate, Calcium Pantothenate, Biotin, Thiamine Mononitrate (source of vitamin B1), Vitamin B12 Supplement, Niacin, Riboflavin Supplement (source of vitamin B2), Inositol, Pyridoxine Hydrochloride (source of vitamin B6), Vitamin D3 Supplement, Folic Acid), Calcium Carbonate, Monosodium Phosphate, DL-Methionine, Rosemary Extract.
Orijen Adult: Fresh boneless chicken, chicken meal, turkey meal, russet potato,
fresh pacific salmon (a natural source of DHA and EPA),
herring meal, sweet potato, peas,
fresh lake whitefish, fresh northern walleye, chicken fat (naturally preserved with vitamin E and citric acid), chicken liver, salmon meal, fresh turkey, fresh whole eggs,
fresh deboned herring, sun-cured alfalfa, salmon oil, chicory root, dehydrated organic kelp, pumpkin, carrots, spinach, turnip greens, apples, cranberries, saskatoon berries, black currants, choline chloride, psyllium, licorice root, angelica root, fenugreek, marigold flowers, sweet fennel, peppermint leaf, chamomile flowers, dandelion, summer savory, rosemary, sea salt, vitamin supplements (vitamin A, vitamin D3, vitamin E, niacin, vitamin C, thiamine mononitrate, riboflavin, vitamin B5, vitamin B6, folic acid, biotin, vitamin B12), mineral supplements (zinc proteinate, iron proteinate, manganese proteinate, copper proteinate, selenium)
Here's a great review on Iams (listed as 2 star on here, 1 star on dogfoodanalysis.com):
Iams ProActive Health Smart Puppy Review and Rating