I have gone to the source and bought off the top 4-5 Chinese sites. Slow, but so far no issues.

Walmart occasionally, but their website is terrible and selection limited.

Microcenter for pc parts.

eBay for a few things.

Adorama and the other big NY camera seller (edit: B&H) often have deals on things like laptops.

Rock auto for car parts. Car-part.com for used car parts when my wife hits yet another deer.

Amazon, still way too much.

Bol.com. Though it only works in The Netherlands and Flanders.

I really don't like amazon. They are a scummy business that try to exploit their workers as much as possible. But jesus it's hard to find competition.. I sometimes end up using Amazon as it's mostly the less expensive choise unfortunately. My sister buys loads of books from there and I get it. They got better prices for that as well..

I use Target most, I think. For random household stuff I can’t get through Target I use Meijer (it’s a grocery+ store) or the local Ace Hardware and do same day pickup.

Honestly those cover probably 75% of purchases. Everything else I google until I find what I want, then spend a couple hours trying to decide if the site is legit or if I can find the manufacturer direct.

Niche category, but Board Game Oracle is great for comparing online prices for board games across sites, and seeing what's on sale

leboncoin.fr I'm in France. It's our local craigslist.

Interestingly Amazon is almost non existent in Switzerland. I think they didn't ship or only with high fees in the first years so it never became famous. We have our own solutions like galaxus.ch or brack.ch. I only ordered twice on Amazon and that just because the products were not available in any other shop.

EBay

If you're a gal, you might like Zulily for clothes, shoes and household items. I've bought more than several things there and been very pleased. Delivery takes forever tho'

Target. Best Buy. Walmart, if I have to. The Shop app is pretty good.