A comparison of R, Matlab, SAS, Stata, and SPSS for their support of fifty-seven (57) statistical functions.
I have not verified the analysis but it is reported that R and Matlab support all fifty-seven (57), SAS supports forty-two (42), Stata supports twenty-nine (29) and SPSS supports a mere twenty (20).
Since R is open-source software, you can verify support of the statistical functions you need before looking at other software.
I first saw this at Table comparing the statistical capabilities of software packages by David Smith.
David mentions the table does not include Julia or Python. It also doesn’t include Mathematica. Having all of these compared in one table could be very useful. Sing out if you see such a table. Thanks!