Personally, I don't like Science Diet. Here are the ingredients for Z/D:

Dried potato products, hydrolyzed chicken liver, potato starch, vegetable oil (preserved with BHA, propyl gallate and citric acid), hydrolyzed chicken, powdered cellulose, glyceryl monostearate, DL-methionine, taurine, ethoxyquin (a preservative), minerals (calcium sulfate, dicalcium phosphate, salt, calcium carbonate, ferrous sulfate, zinc oxide, copper sulfate, manganous oxide, calcium iodate, sodium selenite), vitamins (choline chloride, vitamin A supplement, vitamin D3 supplement, vitamin E supplement, niacin, thiamine mononitrate, calcium pantothenate, pyridoxine hydrochloride, riboflavin, folic acid, biotin, vitamin B12 supplement).
Now, definitions from my own website:
BHA (Butylated Hydroxysanisole) & BHT (Butylated Hydroxytoluene) - Often seen together, these carcinogenic chemical preservatives have been known to cause cancer, tumors, epilepsy, kidney failure, and a number of other things. A dog who eats food containing one or both of these has a 60% chance of developing urinary stones.
Propyl gallate - Tendency to cause the blood disorder, methemoglobinemia.
Ethoxyquin - Ethoxyquin is a chemical preservative that carries specific toxins. These toxins have been known to cause itchy skin, lethargy, hair loss, thyroid problems, reproductive disorders, birth defects, epilepsy, cancer, and stillbirth. The chemical was developed by a company as a rubber hardener. It is also used as a herbicide and insecticide. In Canada it is illegal in human foods. in the US, over 100 ppm illegal in human foods.

I also prefer a food that has meat as the first ingredient, and in the second or third ingredient too. This formula doesn't have meat until the 5th ingredient. I've heard some good things about Wellness's allergy formula. Does Innova have an allergy formula?