I have just finished my second year at university now (Wiiiiiiiiii) and I have a bit of time before I start work and I was thinking about maybe teaching myself a new programming language, but I was wondering if it is really worth it or if my time is better spend working on a personal project in a language I already know?

So far I know C++, C#, Javascript and a bit of a few scripting languages. I am by no means an expert in any of them.
If I were to learn a new language what would you recommend? I have heard that learning a new language is good as it might give you a different way of thinking about problems and make you a overall better programmer.

Thanks and wiiiiiiiiiiiiiiiiiiii again for completing the year