In case anyone is wondering what I use, here's a short list:
Computer/electronics, I visit Newegg. (I haven't been thrilled with them moving into other areas like Auto parts, etc. but they seem alright for the time being.)
Hardware or similar, I go with Tractor Supply Co, Home Depot, or Lowes.
Music, I go with 7Digital.
Car stuff, I have used NAPA in the past, but I hate that they don't store order history for over 1 year. Also, their search function is not great, and their selection is somewhat limited.
General stuff, I've tried to use Walmart for stuff like pillows or sheets or whatever, but most of the stuff they offer is also offered by Amazon, and Amazon is usually stocked better and generally a few dollars cheaper. I've been weary of trying out sites like Aliexpress.
It's frustrating because it seems like Amazon just generally has a larger selection than most other offerings out there. For more niche subjects, I feel like I have some reasonable options, but when it comes to more broad subjects, it feels like it's Amazon or nothing.