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.

>>15
I think you never tried German.
English is insultingly easy. Even the spelling follows SOME kind of rules. Hell, even the irregular verbs follow a rule!
As an example, how you are saying "to go" (-> "Gehen" in German) in both languages:
I go
You go
He/she/it goes
We go
You go
They go

Ich gehe
Du gehst
Er/sie/es geht
Wir gehen
Ihr geht
Sie gehen

(And if you learned this by heart? Congratulations! Now you can apply this rule to... The word "gehen". And nothing more.)

So stop saying English is hard. >.>
It's only hard if you are from the east.

(I'm German myself btw. Started teaching myself English because there were no English lessons in third class... And when I did get English lessons, it got even easier.)