Earlier quoted context omitted.
1982-1989 MS DOS 1988-1996 Unix - first SCO, then Linux (since '91) 1994-2006 Windows - mostly NT 2002-??? macOS 2011-??? Linux Yes, there's overlap, and yes, I'm currently considering Windows again :)
Thanks. And yes, needs/utility vary. Any CPM, Classic Mac, or BeOS experience by chance? (Or others.)
And plenty of others, just never as the main system.