In truth, C# was the "top contender" because it was the only contender. Sorry for the misleading way I phrased it. My main reason for using Java is for the eas

In truth, C# was the "top contender" because it was the only contender. Sorry for the misleading way I phrased it. My main reason for using Java is for the easy cross-platform development. Most of what I code are basic GUI apps that do conversions between spreadsheets and various file formats. Java's "compile once, run everywhere", with its GUI support and many libraries, is exactly what I'm looking for. When I heard that .NET was open-sourced and getting support for all platforms, I thought that meant it could be an actual competitor to Java for my use-case. As I've learned from the responses here, it's actually not, and my fears of running into major parts of the ecosystem that are still proprietary were well-founded. I don't need to worry about "future" proprietary extensions: they're already here!