I take it that it's not popular around here because this site is full of Apple lovers, but there is not denying that C# is 'Java done right/better', so I really see no reason to use Java over C#.
Furthermore C# has the best IDE in the world (Visual Studio), it has a lot better performance than Ruby for instance, it has a sublime integration with web services/databases/etc., it has great documentation (MSDN)...
Furthermore C# has the best IDE in the world (Visual Studio), it has a lot better performance than Ruby for instance, it has a sublime integration with web services/databases/etc., it has great documentation (MSDN)...