I completed your survey. I hope it helps in the research you are conducting.
I prefer mempool.space. I used to navigate to Blockchair and Blockstream in the past, but I find mempool.space much faster and more lightweight. And there are no ads and other nonsense. When it comes to use cases, most people use block explorers to check the status of a sent/received transaction. It's not the most recommended method to do it, especially over the clearnet. Blockchain explorers are great honeypots that hold data on who searches and looks for what, since most of the times people are looking at their own addresses.
At least when you use one, you can pick a site that works over TOR. Or just check the status of your transactions in your native wallet app and don't lookup your own addresses over blockchain explorers at all. It's hard to stick to it though.