Science Diet, Iams, Puke-a-nooba, and Alpo are poor quality foods.
Science Diet Adult Original has ground corn as the second listed ingredient (after "chicken" which is actually about 80% water so corn is the #1 ingredient), followed by two more grains and then chicken by-product meal. There is also corn gluten meal in Science Diet... blech!
In a kibble, you want a named meat meal as the first ingredient (or if the first ingredient is a named meat, it should be immediately followed by a named meat meal). There should be no byproducts or unnamed meat sources (i.e. poultry meal, meat meal, animal byproducts, etc.)
If you want to feed the best, SciDiet, Euk, and Alpo certainly aren't the best. Orijen, Canidae, Innova, California Natural, Blue Buffalo, Timberwolf Organics, Taste of the Wild... these are all good foods. There are more quality foods as well, but these are the just the ones off the top of my head.
Where are you located? We Chazzers can help you find a close-by retailer that carries a high quality diet if you'd like!
PS - vets recommend Hills because they get kickbacks from the company. Their nutrition classes are taught by Hills representatives. They get Hills for VERY cheap, the last time I worked at a facility that offered the veterinary Hill's discount, we could get Science Diet for 10 cents a pound. I never bought a single bag, I stayed with my high quality kibble regardless of the cheapo price I was offered on Hill's.