Home made blender mush is probably the best, followd by Rod's Food, other frozen (needs to be rinsed with RODI to drop the phosphates), freeze dried krill, etc.
It really depends on the fish. Herbivores need algae like nori (seaweed used for sushi wrap).
In most cases you want to feed sparingly. I feed the tank on Wednesday's and Saturday's with nori almost every other day.