Costco gets you the best deal, Walmart and the dollar stores only sell garbage at the lowest possible cost, Amazon sells literally everything and has converted over the years from having the best deals to having the fastest logistics, and then there's whatever niche specialist suppliers are left like digikey for electronics parts etc.
Old Navy's clothing has typically been disposable trash. And most of it still is - generally anything they make out of cotton.
But their Old Navy Active line, specifically their "Breathe ON" fabric, is pretty durable and has really kept me cool throughout this crazy hot summer. They also sell tall and extended sizes which I appreciate. Tall sizes are typically so hard to find. These are not heirloom clothing items, but they've shown little wear over several summers.
This is functional clothing, not anything particularly fashionable. And lest this seem like an viral marketing post, let me restate that most of their lineup is still trash.
 I use one of their credit cards to pay for things and the rewards mean I can buy some of this stuff for cost of shipping or less.