Is that the measure: a complete OS? When exactly did GNU ship a complete OS?
IMHO none of the above is relevant to the question which was first. IMHO both were not first. IBM, among others, were shipping source code with their product, until they didn't. OSS is and was a reaction to an only object model. And there were seeds at Berkeley and MIT.
And Stallman isn't strictly responsible for the MIT strain. As Keith Packard said in his "A Political History of X", the X11 project chose not use the GPL license, because Stallman was simply too annoying.