That was true 5 years ago but with the quality issues on Amazon, I've found myself buying more on eBay.
Finally, Amazon's marketplace is just not navigable. Their search is pathetically bad, and this is nothing new, it's been a common complaint for years. Some fairly massive amount of their traffic is inbound from Google searches like "some product amazon" just because of how pathetically bad it is. The only other reasonable way to navigate their site is if their similar product suggestions or "commonly bought together" happens to nail the item you were looking for.
I've had searches where adding an additional keyword that is in the product title will actually cause the product to disappear from the search. What in the actual fuck.
Their recommendation engine for related prducts used to be nice but that's been replaced by sponsored products which lowers the quality.
Now, the only way I use Amazon's search is when I have a SKU or part number and type it in directly. But I also do that in Google and often find the same thing elsewhere at similar or less cost (including shipping, though to be fair it may take a day or 2 longer).
eBay's search is still one of the best for me, in that it respects the keywords I put in and allows for extended query syntax to really hunt something down (which then can be turned into a saved search).
One of the most creative things I found on eBay was tool rental. I needed a tool to replace the bearings on my washing machine, and a seller was selling one explicitely as a rental: tool was charged about $120, with $35 shipping. When done, sent it back for a refund. The "shipping" included the rental fee and shipping both ways.
The one that they're missing that I really wish they would include is "multi item BIN" formats. People will list a $1 item so that they're the first result that comes up, and then the item you're looking for is high priced. The prices are in fact so high that I go out of my way to try and exclude these items using "not" keywords, setting a minimum price, and filtering to US only, which collectively get most of them.
I have a lot of saved searches for "rare" items that only get listed infrequently, or for items that I'm waiting to come down in price.
The contrast between the way those two sites handle their search is stark.
That's what I thought until I was scammed by a Chinese on eBay... after countless emails, calls, even police reports, eBay did not return the 800 dollars I lost... not sure if it's an isolated case but it was pretty frustrating.