Oh, they're all good, but Alexis Smith's acid delivery seemed not only well-performed in 1971--it seemed shocking.
Her performance was the musical-theater equivalent of the first performances of Hedda Gabler: the reaction of the audience was "People don't do that sort of thing! They don't say that sort of thing! They don't think that sort of thing--or, if they do, they keep it to themselves."
But of course, the brilliance of Sondheim (and his collaborators) was that, in reality, every woman in the audience (and some of the men) had indeed thought that sort of thing, many times, and had always wanted to say it.
Alexis expressed all that, dazzlingly. And then she came out at the end of the show and dazzled us again.
For anyone who saw that performance, hers is the greatest rendition.