I know some people would do veggies for one meal and 1-2 pellets for the other meal, but I think a both should be in the same meal. I would give them one mouthful of pellet (so roughly one pellet) to two mouthfuls of veggies. This also depends a bit on the size of the fish. Large fish can obviously eat larger mouthfuls and hold more food in the GI tract.
Young goldfish need a lot of protein, between 45% and 40%. Older goldfish (3+ years) are the ones that need between 25% and 30% protein. That would be a pretty good staple diet, but with older goldfish I would supplement with more veggies.
Well I looked into NLS goldfish formula, but it looks like it's meat based like the betta formula, and isn't goldfish food supposed to have under 30% protein? The goldfish formula has 34%, which is only 3 percent less than the betta formula...
New Life Spectrum, hands down. If you've got new goldies, try to get one the higher protein formulas as the goldfish formula is a little lower in protein than I would like for a young goldfish. Some of the cichlid formulas might fit the bill.