My choice would be French and the reasons abound:
What do we know about Korean culture and its cultural achievements? They invented the Tae-Kwon-Do, they are one of the "Asian Tigers", they have two major competitors in the economic global arena (Samsung and Hyundai) and they eat dog and horse meat. :-(
Apart that, their language is completely alien to a westerner. You can't count on your previous knowledge of the languages you already know. To make things worse, you'´ll have to learn a completly new set of symbols because they have their private alphabet.
A language is, above all, a tool that we employ to communicate, to learn and expand our vision of the world. Once you have learned Korean, who will be the persons you will talk to using it? Where are they located? What opportunities you will have to use (and maintain) this new knowledge?
On the other hand: French is the lingua franca of diplomacy. It is spoken in Canadá, Belgium, France, Switzerland and a lot of countries in Africa, Pacific and Caribe.
It is a romance language, not too hard to learn for someone who already knows Spanish.
France is one of the most advanced economies of the modern world. It has lots of history and a huge tradition. They invented "la dance", "la gastronomie", "haute couture", among others. They have a very strong literature. Louis XIV, Napoléon, Victor Hugo, Debussis, Rodin, Dirac, Camus, were all French (Can you name a single Korean universal personality?)
Of course, each people has its own culture and history. And each one of them has its own value. However, the volume of realizations made by the French civilization has no parallel in modern world. And their language is the way to access all of that, without brokers, "in natura", first hand.
And there is also Paris!
If I were you, my dear friend, "je voudrais parlez français!"
No doubt about it.
;-)
