"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.