I try to go to manufacturers own online store if they have one. Or a local retailer. Or a specialty online seller. Or Walmart but they have third party sellers too so you have to avoid those.
Not sure which you're asking about but, for example, Best Buy price matches Amazon for items where they overlap. And then I can go get the product right away without waiting for shipping. Or paying for Prime. Or supporting Amazon.
In Germany e.g. Galaxus works fine for many things. Also eBay surprisingly works better for many things because it has more filters, e.g. if you want to buy wood or window shades etc.
eBay has become a cesspool though, with their silly login requiring phone number and so on. I still remember I had a completely fine Kleinanzeigen account at the beginning of the Pandemic, because I wanted to offer math and computer stuff help for students and put an ad for that on kleinanzeigen. (Didn't ever get a request that was worth taking seriously.) Then at some point later, I suddenly was no longer allowed to log in, unless I disclose my phone number. What a shit. Since then that account sits stale or might already be deleted.
Please name one
Genuinely asking