You are exactly right about AlleyCat. Not only is it full of by-products and filler ingredients but it also has red dyed pieces which cats cannot digest and I have read that they are carcinogenic. Basically if you can buy it at the grocery store, it is not good. There are a couple exceptions but basically that is how it works. A step in the right direction would be to go to a pet supply store near you and look for food with no by-products. That will be a great step up while you are learning what is good and what is not so good cat food.
Personally I feed Premium Edge, Merrick and Wellness. Occasionally an off brand of canned food like Friskies or Whiskas, but I try to avoid those, it is a rare treat that my cats will get that stuff.
One cat eats Merrick canned and a bit of Royal Canin dry/Hills r/d (until it's gone, then switching to something else). My other cat eats Hills k/d for her kidney problems. Unfortunately, she's not big on canned.
Alley Cat is very low-quality and not very healthy. Here are the ingredients of one formula:
Alley Cat Chicken and Tuna Flavors Dry Cat Food Ingredients:
Ground yellow corn, corn gluten meal, soybean meal, chicken by-product meal, animal fat preserved with mixed tocopherols (source of vitamin E), ocean fish meal, tuna meal, calcium carbonate, phosphoric acid, salt, choline chloride, brewers dried yeast, dicalcium phosphate, animal digest, tetra sodium pyrophosphate, taurine, zinc sulfate, ferrous sulfate (source of iron), niacin, manganese sulfate, vitamin E supplement, red 40, calcium pantothenate, L-alanine, copper sulfate, vitamin A supplement, rosemary extract, pyridoxine hydrochloride (source of Vitamin B6), vitamin D supplement, biotin, menadione sodium bisulfite complex (source of vitamin K activity L-4511
Personally I use Wellness, Innova and By Nature for my cats. I would recommend the By Nature or By Nature Organics, they are very very good foods and plus they are now selling them at Petsmart stores so they're easier to find.
I use Nutro Natural Choice and Natural Balance for wet food. For snacking, I use Nutro Natural Choice dry food. I buy it because it's good quality, affordable and my kitty loves it (she's very picky).