I think Omega One and New Life Spectrum are the best that are easily available. Like Mr. V said: frozen brine shrimp or frozen daphnia a few times a week to keep them regular.
I have an older male who will eat only frozen blood worms---so spoiled. Also nice to have a little garlic juice around, in case they getv fussy. Good for digestion, too.
I've been having luck with the carnivore fish-food being offered by reptile specialist Allen Repashy. All meaty stuff with a few veggies and NO filler. Comes in powder form. You mix it with boiling water and it kind of gels up. Took a few tries, but now my two younger males jump for the stuff.
I was going to post the ingredients here, but Google isn't working for me right now. Maybe later.