It is important to learn something you will actually use, if you love Italy- learn Italian. If you cant decide which country you like the most then learn a useful language spoken by many people (eg. Mandarin, Spanish, Hindi, Arabic or Portuguese.)
It also depends what you know already, and how hard you want to try.
For instance if you want it to be easier and already know French then learn something similar (another of the Romance languages) like Italian. But if you want to challenge yourself and already studied for instance Spanish, learn something different like Japanese.
If you still have no idea then I will also tell you how much I enjoy the languages I study/have studied. I really enjoyed Japanese when I studied it but don't do it anymore, it is very interesting and different. Or you could be completely different and study sign language or a dead language, I used to study Latin. I wasn't into Latin but that is just my opinion. I also study Russian and French, I enjoy Russian much more- but this is just my opinion.
What's the main reason you want to learn that new language?
Business? Personal interest? Showing off?
Business? Chinese is the obvious choice in that region.
Personal interest? Well, only you know. Pick that language.
Showing off? Pick a rare small area language... like maybe Faroese.