My personal criteria for canned cat food selection is that it does NOT contain any BHA, BHT, ethoxyquin, carrageenan, or any type of fruit or vegetable whole, starch or gluten (corn, wheat, rice, soy, barley, etc.) and lists a muscle meat as the primary ingredient. By "muscle meat" I mean the first ingredient listed should be something like chicken, turkey, salmon, etc. and not "chicken by-products", or "chicken meal" or even "water necessary to..." which I see on a lot of canned food as the primary ingredient.
Now some people will say that you should avoid any type of "by-product" all together, but foods that do not have any by-products are generally much higher in fat content than foods that do contain by-products. For this reason I don't mind by-products as long as they are not the primary ingredient.
For instance the first 7 ingredients of Fancy Feast Cod, Sole & Shrimp Feast are: "Cod, liver, meat by-products, fish, fish broth, sole, shrimp", now compare that to first 7 ingredients of 9-Lives Seafood Platter: "Meat by-products, water sufficient for processing, poultry by-products, fish, chicken, calcium carbonate, guar gum". Notice that in the Fancy Feast by-products don't appear until the third ingredient, and good muscle and organ meat are 5 of the first 7 ingredients. Now looking at the 9-Lives you see that by-products are the very first ingredient and then water is the next ingredient, followed by more by-product. This means 9-Lives is a much lower quality food. Also every flavor of 9-Lives I have seen contains carrageenan which can cause inflammation in your cat.
One more thing just because one flavor of a particular brand is good, does NOT mean that all flavors are just as good. For instance some flavors of Fancy Feast do have by-products as a first ingredient OR contain corn, soy, or other plant based protein which is not very good for your cat. I do not buy these flavors. The bottom line is learn to read the ingredients and label information to make smart choices that you can afford.