The important thing to remember is that any feeder is more than a sum of its parts. Proper gutloading will increase the value of any feeder that can be gutloaded. Dusting is necessary in almost all situations.
Also a definition of what you value in nutritional composition is important. Butterworms are naturally high in calcium, as are silkworms and phoenix worms. Phoenix Worms are the only ones with a proper Ca ratio. Of these, phoenix worms are the only ones that can be gutloaded.
Acceptance + basic nutritional value + ease of gutloading + ease of dusting + market availability + afforability = best feeder.