What do you mean by best? Do you want a wafer for an herbivorous pleco, or a more carnivorous one? If the former, Hikari is a good one. I myself prefer NLS, New Life Spectrum, as the garlic is an appetite stimulant, and the primary ingredient is krill and fish meal, not just fish meal, though I have primarily carnivorous plecos. I know some people object to Hikari having wheat meal and germ being the second and third ingredient. Something I plan to try is spirulina sticks, which would maybe be better for the more herbivorous plecos. They are cheaper in bulk than Hikari, and have a higher concentration of algae and plant material.