Either Japanese or Russian. Japanese because I already know a bit and would like to finally be communicative in it, and Russian because the similarities between that language and mine are not big enough to make it easy to learn, but are just enough in the right places to cause incredible confusion. And I think it might come in handy one day. It also doesn't help that all the older generations here speak at least a bit of Russian. I don't like to be the person who doesn't know a language.