The first thing I look at are the ingredients. The first few should be some type of aquatic protein (fish, shrimp, etc.). If, instead, you see grain fillers as the first few ingredients, don't waste your money.
Wardley's Shrimp Pellets:
Shrimp meal, wheat flour, soy protein concentrate, hydrolyzed fish protein, corn gluten meal, brewers dried yeast, dried beet pulp, wheat germ meal, plankton, l-ascorbyl-2-polyphosphate (source of vitamin C).
Omega One Shrimp Pellets:
Whole Shrimp, Whole Salmon, Cod, Whole Herring, Seafood Mix (including Krill, Rockfish, Shrimp, Squid, Clams, Salmon Eggs and Octopus), Wheat Flour, Fresh Kelp, Spirulina, Lecithin, Astaxanthin, L-Ascorbyl-2-Phosphate (source of vitamin C), Natural and Artifical Colours, Vitamin A Acetate, Vitamin D3 Supplement, Vitamin E Supplement, Vitamin B12 Supplement, Riboflavin, Niacin, Pantothenic Acid, Folic Acid, Biotin, Inositol, Tocopherol (preservative), Ethoxyquin (preservative).
I'd go with the Omega One.