At my last job, I was a C#/F# dev. Recently changed jobs and learned that even in 2018, .NET is a dirty word at many companies.
The JVM and .NET are presently about the same capability-wise, but Java is (or at least, is perceived as) much easier and cheaper to freely experiment with. Unless you need to use C# for some deep Windows integration, this makes Java the obvious choice for anyone without sunk costs in the .NET ecosystem.