IMO, both IAMS and Eukanuba are crap. Especially for the money.
Dogs are carnivores, which means their diet should be comprised primarily (and some will argue exclusively) of meat. Many dog foods, IAMS and Eukanuba included, are heavily grain based.
When shopping dog foods you need to learn to read lables. The ingredients listed first in the ingredients list are those that make up the highest percentage of the food. Good foods have meat sources as their primary ingredients and will contain many meat sources in the first several ingredients listed. Poorer quality foods will have lots of grains (corn, wheat, rice, oats) in the first few ingredients.
Some other things are to try to avoid by-products, and that Chicken Meal is better than just Chicken, since meal has had the water removed prior to weighing whereas Chicken is weighed (and thus assigned it's spot on the ingredients list) with the water included. Once the water is removed from Chicken, it's going to move down the list.
For example, Eukanuba's GSD formula's first 10 ingredients:
"Chicken, Corn Meal, Ground Whole Grain Sorghum, Chicken By-Product Meal (Natural source of Chondroitin Sulfate and Glucosamine), Brewers Rice, Fish meal, Natural Chicken Flavor, Dried Beet Pulp (sugar removed), Dried Egg Product, Brewers Dried Yeast,..."
For the same money you can feed:
"Chicken Meal, Turkey Meal, Brown Rice, White Rice, Lamb Meal, Chicken Fat (preserved with Mixed Tocopherols), Herring Meal, Flax Seed, Sun Cured Alfalfa Meal, Sunflower Oil, Chicken,..." More meat based ingredients, less grains, and the grain that is there (rice) is much better than corn.
Also, the "breed specific" foods made by Eukanuba and others are more marketing gimick than anything else. The ingredients are still relatively poor.