C#; no. It's Microsoft's version of Java.
C/C++ would have some advantages on Windows machines, and possibly other machines. I've never played with C/C++ in depth though, and thus I can't say what it can or cannot do more efficiently than other languages.
Java can be constructed into several forms. Code converters can create executable files out of Java. Executable JARS can be supported across many operating systems. Java also has, as you know, a heavy mobile operating system following.
@MaSOuD C# actually came out after Java, as a competitive ploy by Microsoft. Even then it failed to catch fire with the tech world, outside of Windows. So C# is more comparable to C/C++ since they both are predominately Windows related, and narrowly scoped at that. It is in that respect that Microsoft is much like Apple, making specialized products with a specific audience in mind, rather than a product that can be expanded, and adapted to many other applications.
@Sorasyn I know when C# came out. Still C# has more usage and grown so faster than Java considering that Java is cross platform and C# is only on Windows (Just like you mentioned.)
However, there's the Mono Project that brings C# on Mac & Linux & Android. :)
Java is just so ugly, and hard to work with. Since there are no good IDEs for it comparing to Visual Studio for C#.
Suppose I'll find out more about C# in the final weeks of the semester, so I'll be able to better judge it's usability. I don't much like IDEs to start off with, but for bigger projects I'll use NetBeans which is ok. It's UI builder is a tad constricting but it's manageable for the most part. However, their syntax and overall code structure are eerily similar though.
Python, perhaps? Or you could expand upon your knowledge in Java among other languages.