I prefer to learn Asian languages like Arabic, Hindi, Malay, Indonesian, Korean, Japanese, or even Mandarin. It's because i personally think that there are still so many people from asian countries who don't speak english. It'll be easier for us to communicate with them if we speak their languages. Even though these languages might be hard to be learned remembering the lack of these languages' sources we'd find on the internet, it's worth the try, really. :)