Also, running .NET on Linux? Yeah, again, MS is opening up, but I dare to say it will lag behind Windows forever. Developing .NET on Linux? I wouldn't even try. Yeah there are some niches like Unity and Xamarin, which ought to work on Linux, but I'm not betting on those.

Java, however, is much more, perhaps almost completely, equal on Linux, Mac and Windows, for running applications, services and development.