Japanese, for I can already speak English.

lol

I would choose German because I am very much interested in it. 

I'd like to learn French, it's a beautiful language and  also it's interesting.
I would like to travel to France , i have heard it has awesome place to visit, like castles,beautiful beaches and "plazas", all the french culture, the Museums  like Luvre.

I like to choose  italian language,because it sounds great :)

Well, I like languages in general but I find the process of learning a new language very interesting and funny that is difficult for me to answer your question. Maybe out of necesity i will say that english would be. Because i think that english is the most useful language for bussiness, for technology and many other things, I have been learning english for many years and I still have some problems not as much as I had when I started, but I would like to speak english almost like a native speaker. However I have enjoyed my process and maybe if that technology or miracle will exist maybe I will decline and I will opt for learning a new language studying and making my best effort every day in order to achieve my goal.