I agree with Tiffi. Avoid the 99 cent specials and stick with the big brands (Tetra, Nutrafin, Hikari, Ocean Nutrition, Omega One to name a few).
Variety is the most important thing about your fishs' diet. Fresh veggies, frozen foods, and live worms can be used to supplement any dry fish food. I like to mix up the format too - flake one day, micropellets the next, then sinking tabs, etc. All my fish get spirulina flakes every few days too.
I think I have about 15 different brands/types of fish foods. Most of them were freebies from my monthly aquarium club meeting.