I would recommend... statistics. If you already know Python, learning how to do the same things in a different environment doesn't really add a skill to your r

I would recommend... statistics. If you already know Python, learning how to do the same things in a different environment doesn't really add a skill to your resume. It probably means you can apply for more jobs/work on different projects but for each job/project you would be the same candidate as before. Almost like branching out your skill tree rather than extending it. On the other hand, at a time when importing a library and throwing it on a dataset (without understanding what it actually does) is becoming easier, having a comprehensive understanding of probability, statistics, calculus and linear algebra would be a huge differentiator. As far as languages go, Scala comes up a lot in data science job postings where I live, but my experience is limited only to trying out the Scala API of Spark. Maybe someone with more experience can shed some light on this.