Well for me personally, it depends on the parts. I am a big fan of using OEM only and believe it or not, some OEM parts can be the same price as the aftermarket brands.
However, that said, if i was in a bind for per se an Alternator or Starter, i would use Autozone as they do offer a life time warranty on those types of parts. There Duralast batteries are also made by Johnson Company, the same people who make Interstate batteries.
I do shop at Autozone for my fluids and chemicals seeing as there is one in my town.
If im working on a friends or family vehicle, its all down to them when it comes to parts replacement. I explain the pro’s and con’s of each and let them decide.
But this question all boils down to peoples budgets and finances. Not a lot of people can afford dealer prices for OEM parts.
You get what you pay for when purchasing anything automotive related, period.