Which language should I learn

Hello- my university offers cheap Language courses. I already have learnt conversational Spanish, and need to know what I should go for next.
The choices are:
Arabic
British Sign Language
French
German
Italian
Japanese
Mandarin
Polish
Russian

Considering Polish atm, but have heard it is ridiculously hard.

>>6

Why Japanese?  I'd rather learn Chinese or Arabic on that list.  Japan isn't bad, but most people who learn Japanese do so to read manga in Japanese and act like faggots.

Mandarin is pretty interesting on its own, though I don't know how many speakers you'll find.  Arabic is cool sounding, and due to islam, there are probably a good number of speakers.