Dembe, Partridge, and Geist (2011, pdf), in a paper recently published in
Good company. Both are, in our humble opinion, excellent packages, although we admit to have a preference for one of them.
We should mention that the authors report that SAS usage grew considerably during the study period, and that Stata usage held roughly constant, a conclusion that matches the results in their Table 1, an extract of which is
|% Stata used||48.3||42.6||47.4||46.0|
|% SAS used||37.2||43.1||47.4||42.6|
The authors speculated that the growth of SAS “may have been stimulated by enhancements [...] that gave users the ability to use balanced repeated replication (BRR) and jackknife methods for variance estimation with complex survey data [...]“. Since those features were already in Stata, that sounds reasonable to us.
Let us just say, good company. Good companies.