Still running Snow Leopard 10.68 and no plans to upgrade ... Apple lost it after 10.6 and became something else more like MS.
My old iMac is another story. It's so old it couldn't even be upgraded to High Sierra. I only use it for downloading stuff, but Safari, Google and Firefox can not be upgraded at all. And I had to stop using Safari all together, because it stopped letting me access specific sites that I had been going to for a very long time...kept claiming it couldn't make a secure connection to those sites. I've been using Firefox instead, and it's still performing fine. Knock on wood!
My oldest son used to be a big Mac user, but got tired of Apple's BS, and uses PC's now with Linux. He's the tech geek in the family, but since he hadn't been keeping up to to date with Apple products, I could even ask him for help when my laptop space was disappearing. I'm 71, and cringe every time I think about having to replace one of my old Apple computers. They're not cheap, but I don't know if I'd be able to deal with a PC and Windows.