I think that C# is not much "loved" here, because it's just Microsoft's thing... :D

And Java just looks more professional :D. Too many dummies are using C# here - just compare some Java and C# public forums.

When I would have to develop some multi-platform application and I couldn't use C++ & GTKmm, I would choose Java rather then C#... Java for Linux is developed by it's creator - Sun - but MONO is not developed by Microsoft. So it's just a bigger risc to use it.