You guys wasted 5 pages of this thread arguing over whether to feed one food or multiple when you could have answer the question... sad. It's simple logic that a single pellet brand cannot cover all the dietary needs regardless of the results you have(which I don't refute). As for the using multiple foods I do't see why one would use different pellets(besides veggi and carnivore pellets) at the same time. I currently use sticks(tetra), pellets(aqueon), shrimp(Omega One), and flakes(tetra). The only reason I use sticks is because stimulation and my female jack won't respond to pellets.
To answer the op's question. The best mix(not talking about brands) should be veggi, carnivore,and non-processed foods(bloodworms,shrimp,krill, etc). That's just my opinion.