I've been coding Python for 8 years. Only in the last couple years have I reached a level where I can make a substantive contribution to a large open source project like Pandas. However, contributing to OSS requires not only knowing the language, but also the open source workflow including git, testing, continuous integration, semantic versioning, documentation, etcetera.
I'd recommend Python. It's general purpose, but also a leading language for data science applications, making it a timely choice.
Thank you for the information. Good luck!