NT kernel is pretty solid and thr earlier NT kernel OS such as Win 2000 and XP are solid too. They definitely did not have the security features modern OSes have but security always evolves.
But apart from NT I can't think of a lot more solid products that came out of Microsoft.
Meh, not many indeed. Anyway they adopted the beta to user and improve on the way mindset long time ago. Windows terminal was not very good back then but now it is OK.