just for curiosity... What language is used most here? R? MATLAB? Python? Java?
What for prototype or for production? For example I think MATLAB is mostly used for prototyping, python for both prot. and production...
I couldnt agree more with a vote for R. R is the "Lingua Franca" of the statistics world. It is the definition of cutting edge, while most packages for MATLAB and SAS take several months. The language is very simple to understand as opposed to SAS. It also gives you the power to connect with C/C++/Python and databases.
Consider Revolution Analytics version of R for a bit more performance.
Well, you can PAY for MATLAB, and then either (1) program the stuff you really need from the ground up or (2) PAY MORE for MATLAB toolboxes. And discover that doing useful statistics in MATLAB was an afterthought handled in the increasingly less useful Statistics Toolbox. Or...you can download R for FREE and search for (and find!) the packages you need, which you can also download for FREE.
Lots of small scale production stuff can be done in R. If you're doing something really big (think US census), you probably need to go learn SAS--and get your employer to pay for it.
"Popularity" depends on the community and the definition of "statistics". World-wide, taking a broad view of "statistical inference" as including any methods of drawing conclusions or taking actions based on quantitative data, there is little question that Excel beats all other applications, including R, SAS, Stata, SPSS, and S-Plus. (The links point to different kinds of statistics, but they are highly suggestive, to say the least.) Python and MATLAB aren't even blips in the statistics. I am not saying that this is a good thing or that we should like it: that's just how it is and that's how it's going to stay for a very long time.
We shouldn't draw any inferences from what may appear to be popular "here" in this forum. Commercial software vendors support their own forums, so naturally a place like SE will favor people using less actively supported software, especially free, open-source, and academic solutions.
It should be clear by looking at the most popular tags that R is the most popular language on this site. Whether that makes it the most popular language for statistical analysis can't be inferred directly, but one might suppose as much.
R and SAS have each their pros and cons. I think more statisticians need to embrace the fact that lots of great statistical software is available, rather than endlessly bicker about which is superior.
R is free. SAS is very expensive. R gives you the ability to do just about anything. SAS may or may not. R has amazing graphical abilities. Seeing SAS graphics makes it feel like 1985 all over again. SAS has great customer support. R support = hours of searching mailing list archives. Also with a name like "R", search engine results are often poor. R is extremely slow and does not deal well with large data sets. SAS does fine with large data sets. SAS tends to be more robust. In my experience, when it comes to mixed effects modeling or anything involving design of experiments (such as analyzing crossover designs), SAS is superior.
For large scale, brute force simulations, I use Fortran. I used to use C, but have found Fortran is much easier to use. I've never used MATLAB. If I need statistical power of R but the speed of Fortran, I will write the time-intensive operations (i.e. loops) in Fortran and call the subroutine from R.
My preference goes to Python, and perhaps, Java. First, they are real programming languages. Second, they are the most popular languages (TIOBE Index). You can also convert between these languages using several scripting languages. In the past I use DMelt platform http://jwork.org/dmelt/ to perform statistical calculations, and I was very impressed by the graphics in 2D and 3D, which can be easily achieved for professional papers. R package did not impress me with the graphics.