to be honest, what fascinates me is that microsoft seems to have invested a lot of work the past few years to bring forward a pretty decent line up of integrated products. if you want windows and office like you had, that's fine. and much of the windows 8 UI disaster was actually made up by the press to have a great story, even that one video with the guy's dad. i was shocked when i saw that. then i installed windows…
I imagine, since you say you love C# are you a .Net programmer? Others have pointed out that .Net programmers are Microsoft's biggest cheerleaders these days and have a conflict of interest in speaking about Microsoft's future since maybe they have staked their career on .NET.
So if I were contracted to write something business class in something interpreted, I'd definitely put C# with Mono at the top of the list. It is much nicer than Java to develop in, and has platform parity.