So, here's the deal:

Situation:

-I'm currently at the chapter 9 of Japanese for Busy People.

-I want to study Arabic, I have a textbook for it.

-But I also want to study Korean...

Own thoughts:

Arabic:
Pros - Interesting and important language in today's world, helps understand our Muslim neighbors.
Cons - Just like Chinese, it has many varieties. The spoken language in Morocco differs a lot from the one in Syria. The literary language is good only if you want to read the Qur'an in Arabic.

Japanese:
Pros - I can say more on 4chan than just "kawaii". Plus, Japan is VERY sugoi!
Cons - Craploads of kanji. I already know some of it and the hiragana and katakana syllabaries PLUS I'd never even dare to say "romanji" (hello, it's roomaji FFS..). Japanese is not that important in today's world, though.

Korean:
Pros - I like the language and genuinely want to learn it. It's the easiest one since you don't have to learn craploads of hanja in order to manage.
Cons - Like learning French: where are you going to need it unless you don't move to the damn country in question or start to teach the language yourself?

Conclusion:

Help me...