I'd like to echo what someone else said, which is that certified organic is a hard standard to meet. It's a divisive issue, I know (as is a lot of chicken information) but I would never advocate for choosing a product just because it's earned the certified organic label. Whatever you choose, it should best serve your needs, your flock's health, and your pocketbook. Because chicken keeping should be for everyone.
I weighed a lot of options because I have a smaller flock (10) and it's not too cost-prohibitive for me to go with a fancy non-GMO option. But, they can get VERY expensive if you're buying more than 100 lbs a month. Personally, the certified organic label doesn't mean as much to me as the sustainable tag for the reason that choosing certified organic precludes some excellent sustainable small business farming operations. Organic farming is incredibly challenging to implement and it takes 3 years of those organic practices to yield the first 'certified organic' harvest.
I use Grubbly Farms Little Pecks for my chicks and they're non-GMO but not organic due to the fact that it's made with sustainably grown black soldier fly grubs. Their website claims: "Our grubs are naturally harvested (no hormones, pesticides or funky byproducts) and help reduce food waste from landfills." You can read about how they're harvested
HERE. That said, I plan to switch to Scratch and Peck when my chickens are at laying age because of the brand reputation, organic label, and the fact that it'll ship with the rest of my Chewy order (they have poultry items now!).
I understand why other backyard chicken keepers use brands like Mana Pro, Dumor, and Purina because they're widely available and you can stop by
TSC,
Wal-Mart, etc. on your way home. Also, Grubbly Farms, Scratch and Peck, and other non-GMO options don't have medicated chick starter. They have their reasons but, if that's your preference (as was mine for the first 2 weeks), you're going to need Mana Pro or Dumor.