What is the best language to learn for the future?

I am currently working on my degree in Linguistics and I am going to minor in Spanish. I would like another minor as well but in a different language. I would prefer a language that is not romantic, germanic, or slavic. I really can't decide between Arabic or Mandarin Chinese. I would like to be a professor. I'm learning French on my own time and plan on moving to Italian after since they are derived from Latin as is Spanish. I would just like to know your opinion. Thanks!