I did find a New York Post article about the favorite drinks of all the presidents, but some of the ones they list are more like "this beverage was mentioned once by this president" than actual known favorites.
And there is this video where she talks about a drinking competition with John McCain.
No mention of what brand they were drinking. (It happened in Estonia, so who knows if her favorite was available.) She says it ended in a tie but her former campaign manager Terry McAuliffe and the owner of the restaurant where it took place both say that Clinton won.
I did find where she said that her favorite drink is a vodka martini. That may or may not be code for "put vodka in a cocktail shaker with ice, wave an unopened bottle of Vermouth in the general direction of the shaker, shake, strain into glass." Or not.
I'm going to assume her favorite is Sobieski (because who's going to contradict me?). I think this is a generous assumption - that she cares enough about the flavor and not just what will get her drunk the fastest.