In my area the main stores that are the bulk of the gigs are Stater Bros, Walmart, Costco, Sprouts, Aldi and the chain groceries.

All else being equal my favorite is Aldi, because they are small and there aren't a lot of options, so it is easy and fast to find items. And the lines aren't too long most of the time. If you are doing a Costco or Sams club order at a busy time, you can spend 15+ minutes going through line, which is again money.