I go Omega One Betta Buffet pellets for the most part when not doing live/homemade, and they are very tiny.. are you using the Betta Buffet ones? Or just Omega One pellets... there is a difference.
The flakes for Omega One Betta Buffet actually are a bit healthier then the pellets, but it tends to be easier to feed/clean up pellets over flakes- can be more precise in how much you are feeding.
NLS is great too, Grow formula is a great source of protein.
Either one of those brands, but you have to make sure it fits a betta's specific needs in a diet.