So obviously stores don't blend their own oil, so most contract an existing oil company to bottle their oil. For example Walmart has their SuperTech oil, and all indications are it's a very good oil for the price. Depending on where you are it's either WPP or Shell that bottles the oil for them.
NAPA contracts with Ashland, who own and produce Valvoline. As such you can see that their oils are very very similar to one another.
Or if you want to have some fun (well, BITOG'er "fun"), you can check out something like:
http://www.pqiamerica.com/Feb2014/consolidated5w20ALL.html and look at all the store brand oils that are extremely similar. For example Federated Auto, AutoZone, Advance Auto, O'Reilly's, Traveller, and some others all seem to have very similar additive packages, and the same bottle shapes. They've probably all contracted with the same company, and have very similar oil in their bottles.
Pretty much all the oils you listed in the first post are fine oils to use. Not saying they're top tier and able to compete with the likes of M1, or Amsoil. But they're good oils that will protect your engine just fine.
BTW, Mag 1 isn't a store brand oil, it's the WPP brand oil. Might be the same as SuperTech synthetic, I don't know, but I've never heard anything wrong with it, and I would use it in my engine without hesitation.