I think Mandarin is the way to go. I mean with almost every country vying for the affection of China and its man power and its influence on the economy then speaking the language is a huge advantage on this point. I've seen it first hand how the rights words on the right ears opens doors and create opportunities.
The question is vague. Its not clear what you are talking about. Either you are thinking for changing of your native language or some computer language. Please be precise when questioning.