In general I believe pellets are more nutritious than flakes. For the typical omnivorous community fish to thrive, I think these are good guidelines:
-Once a week frozen/freeze dried nutritious food (blood worms are not very nutritious)
-An omnivorous pellet as the staple
-And some type of vegetable matter like spirulina flakes
In general, variety is king, so you can also add another type of flake like krill flakes or another type of pellet, but these guidelines cover the basics. Hikari Pellets are great, Fluval Bug Bites, Xtreme for krill flakes and spirulina are some I use.