We're just planning for upgrading all our Windows Server 2012 boxes to 2016 or 2019 before they go out of support. This includes our four SAS machines, all on 2012 R2: metadata server, mid-tier server, compute server and VA server. Our SAS version is 9.4M7 (and VA 7.5).
System requirements indicate that both newer versions of Windows are OK. But does anyone have any insights around issues which we might encounter?