regardless of the name or brand, what you want to look for first is if there are fillers in the first 5 or more ingredients on the label. if you see anything that has the words 'gluten', 'starch', 'wheat', 'corn', 'flour', etc in the first part of the ingredients then it is most likely a lower quality food.
for example:
Omega One Veggie Flakes - ingredients: whole salmon, black cod, halibut, whole herring, fresh kelp, spirulina, wheat flour, lecithin..... the list goes on to name preservatives, supplements/vitamins, and such.
Tetra Min Tropical Crisps - Fish meal, dried yeast, corn starch, shrimp meal, wheat gluten, ground brown rice, potato protein, soybean oil, dehulled soybean meal, fish oil, guar gum, dried skim milk, sorbitol, algae meal, lecithin, krill...... goes on to name a bunch of nearly unpronounceable stuff that is supposed to be vitamins, preservatives, and the colour of the food comes from various dyes.
can you tell which of the above foods is better quality/more nutritious/a better choice? i'm not touting the Omega food line here, i just grabbed two jars of food off my tank stand as example.