Depends on the other languages in your tool belt. If you're a relatively junior programmer I'd suggest sticking with python -it has a broad application beyond just data science into things like server management etc. The way it reads is fairly close to other languages and I've seen it used more in industry.
R is a different beast and scripts are quite peculiar in the way they're written. It's very good for numerical analysis, but less intuitive for most programmers to pick up so it's applied in more of an academic setting or companies that specialize in data science.
If you're thinking for a career, I'd find a company that looks like one you'd want to join and reach out to some of them on twitter or linkedin and ask what they used. Heck, it may even turn into a job/internship.