I think most people on here prefer the pellets opposed to flakes since they are easier to measure so you know how much you are feeding and the pellets are a lot less messy in the tank.
My local petco carries both NLS and Omega One pellets/flakes. I think as long as it is a quality food, it doesn't matter if it is flaked or pelleted. There might be a store near you that carries pellets, but if you are fine with feeding flakes, I'd say get them.
This is just my opinion however, someone else might come along with another one.