I've been a C#-devver for the past 4 years, but actually I'd still prefer Java. It's just just the language (or even despite the language), but the .NET ecosystem is... meh. Even when using commercial dev tools (Visual Studio, Xamarin), they are no better than the much more open and free tools for Java. VS still freezes daily in me, Xamarin still is buggy. Granted, I'm not paying for those, my employer does, so why should I care.

But the Java language, JDK and all surrounding development are much more community driven than anything from Microsoft. Yeah, Microsoft these days is more open than ever before, but they still are in total control. I've come to value the freedom of Java, and "true" open source in general, because the C#-world still is restrictive.