Most useful in what context? If you want to pick up a language as quick as possible then C# or Java. Either choice is fine. C# has a lot of potential in the f

Most useful in what context? If you want to pick up a language as quick as possible then C# or Java. Either choice is fine. C# has a lot of potential in the future now Microsoft are making it more open with multi-platform .NET but it is still a way off IMHO. Java is used everywhere and while it isn't all that "cool" it does work well, is easy to write, debug and maintain. Plus I actually quite like JavaFX. It allows me to make a nice looking UI very easily. As great as C#/.NET is you can't use C# for any decent GUI stuff outside of Windows just yet. If you want to get a job then look at what jobs in your area are using.