It depends on where in Europe you are going to study. If in Spain, choose Spanish; if in France, choose French, for example. I would recommend German, generally speaking.

Well, I think a lot of factors need to be taken into consideration, for instance the country you will be based in when you are pursuing university education, countries you want to travel to and have experiences, whether professional or cultural, in, etc. In most cases, universities in the United Kingdom are the most sought after, seeing as how they are typically ranked high in every University Rankings list, and offer exchange semesters in other European countries as well. When I was studying in Europe, I discovered that having English speaking skills was adequate for whatever it was I wished to pursue, but in case you are really looking to diversify your options and have a more varied experience, I would suggest German since most of the students that will end up being your classmates will be from Germany (the country produces the highest number of foreign education seekers in Europe), most exchange semesters that you might end up opting for, are based in German speaking countries like Germany, Switzerland etc., and the country offers a whole lot of internship/job opportunities for recent graduates fluent in English. Spanish would be a useful language to learn too, since the job market in Spain is supposedly much more accepting of foreign language students owing to the diversity that exists within their own borders, although being in Spain would require you to be multilingual to insane extents if you want to set yourself apart from other aspirants in the country in search of foreign education and job opportunities. Although Spain is the best place to be in, if your interests are more "cultural" and "artistic" in nature, which is why I consider Spanish, and German, to be more important than French. Most importantly, chances are that you will have to base yourself in a country where the language you learn ISN'T spoken natively, so that you can set yourself apart from other education/job seekers that are typically present in the country and obtain better opportunities.

Thankyou so much sir for your advice and patience to help me. I really appreciate your kindness. Once again thanks a lot for your comprehensive explanation. Also thankyou for sparing your valuable time in replying to my post.