There’s no stable version anymore. I'm still running El Capitan, and not having any issues. Admittedly, I would have upgraded had my mac been eligible, becaus

There’s no stable version anymore. I'm still running El Capitan, and not having any issues. Admittedly, I would have upgraded had my mac been eligible, because I'm just that sort of person, but there's nothing in Sierra or High Sierra that would make a meaningful difference to me.