[S_A_P]

This guy has always impressed me. He works on Java at Google and spends a large chunk of time being a C# and .NET expert. Obviously C# and Java are semantically close to the point of nearly interchangeable, but the devil is in the details and he seems to have them down.

[V-2]

Java is years behind C# in most aspects. Of course it doesn't mean it follows the same path, but there's less to learn if you switch from (modern) C# to Java than the other way round.