A poor unenlightened soul refuses to acknowledge the primacy of Eydie Gorme in all things musical, so I feel the need to offer a direct comparison.
We’ll take Keely Smith on her home turf, with “I Wish You Love”, the title track from her 1957 debut album.
Here is Eydie Gorme doing what she does best, which is everything:
As I had said to Friar, I’ve got another Keely Smith album (Be My Love) that hasn’t really stood out, and I think it’s because Keely sounds like a lot of other female big band vocalists I’ve heard, where the delivery is flat and a bit projected since there’s generally an orchestra behind them whereas Eydie is more pop/jazz influenced, where the notes are rounder and the presentation more intimate.
Your actual mileage may vary, but understand that no matter what scientific measurement you apply, Eydie Gorme is always the best. Because no matter what your subjective understanding of reality is at any given time, reality is as it is.
Either way, the research into deciding the question is a pleasant afternoon. ;-)