Exotic language vs. world language?

I am going to study a new language this fall as a part of university programme. I already speak fluent English, Swedish and also speak German and French relatively well. I'm not sure what I want to do in the future but I am wondering if anyone has any suggestions on whether it is more beneficial in the world today to have an exotic langauge on your resume (say Arabic, Swahili or Japanese) or another world language (Spanish)?