Hi Ecrin, The only one who can answer this question is you. What are your plans for the future? Which one would be more useful to you, ie. who will you be dealing with in future? Do you plan to work with a German-, Russian- or Spanish-speaking business? Do you plan to live somewhere else in future? Even if you choose one for university, there's nothing stopping you from learning the others. :)

Chose one and stick with it. They're all the same.

All these language would be best for you, Ecrin, except of English! ;)