Which of these languages...

is the most worth learning, in your opinion, and why?

Russian, Turkish, Urdu, Punjabi, Korean, Hindi, Arabic, Chinese, Bengali.

Additionally, which countries that speak these languages are pleasant and which are shitty?

>>1
They're all shitty, just in different ways, if you just want to be safe then China, Turkey and to a lesser extent Korea.
Still, In Turkey I still feel like watching my back. Never been to China, but my ex travels there a lot, she feels safe to a degree.