Some additional thoughts.
The programming language 'per se' is only a tool. All languages were designed to make some type of constructs more easy to build than others. And the knowledge and mastery of a programming language is more important and effective than the features of that language compared to others.
As far as I can see there are two dimensions of this question. The first dimension is the ability to explore, build proof of concepts or models at a fast pace, eventually having at hand enough tools to study what is going on (like statistical tests, graphics, measurement tools, etc). This kind of activity is usually preferred by researchers and data scientists (I always wonder what that means, but I use this term for its loose definition). They tend to rely on well-known and verified instruments, which can be used for proofs or arguments.
The second dimension is the ability to extend, change, improve or even create tools, algorithms or models. In order to achieve that you need a proper programming language. Roughly all of them are the same. If you work for a company, than you depend a lot on the company's infrastructure, internal culture and your choices diminish significantly. Also, when you want to implement an algorithm for production use, you have to trust the implementation. And implementing in another language which you do not master will not help you much.
I tend to favor for the first type of activity the R ecosystem. You have a great community, a huge set of tools, proofs that these tools works as expected. Also, you can consider Python, Octave (to name a few), which are reliable candidates.
For the second task, you have to think before at what you really want. If you want robust production ready tools, then C/C++, Java, C# are great candidates. I consider Python as a second citizen in this category, together with Scala and friends. I do not want to start a flame war, it's my opinion only. But after more than 17 years as a developer, I tend to prefer a strict contract and my knowledge, than the freedom to do whatever you might think of (like it happens with a lot of dynamic languages).
Personally, I want to learn as much as possible. I decided that I have to choose the hard way, which means to implement everything from scratch myself. I use R as a model and inspiration. It has great treasures in libraries and a lot of experience distilled. However, R as a programming language is a nightmare for me. So I decided to use Java, and use no additional library. That is only because of my experience, and nothing else.
If you have time, the best thing you can do is to spend some time with all these things. In this way you will earn for yourself the best answer possible, fitted for you. Dijkstra said once that the tools influence the way you think, so it is advisable to know your tools before letting them to model how you think. You can read more about that in his famous paper called The Humble Programmer