>>3123728OP just pick whatever seems to come naturally for you. I'm biased, but Spanish always seemed relatively easy.
Pick a global language, preferably one where English won't get your around as easily. Mandarin, Russian, and Spanish are all solid choices. Don't bother learning a language that isn't recognized as an official government language. Punjabi, Javanese, and some Indian languages come to mind as languages that are "worth learning," but not as much as the others I listed.
Arabic is also a solid language choice if you're committed. Personally, global terrorism has reduced the number of Arabic speaking countries that are safe enough for white Westerners to the point where it's no longer worth the effort of learning.
When you can already fluently read Spanish and speak enough of it, it's really hard to justify bothering to learn a third language when your first one is english.
I'm all for learning languages, but it's never been my forte and any more efforts would be a waste.