I perceive Edith Piaf's voicing/delivery in the context of when it was popular. Her popularity soared in the war years, this is a voice of patriotism, resolve.
Joan Baez sometimes does the vibrato thing to excess, nothing near these 'divas' so popular today, way over the top vocal gymnastics bugs me to no end. Sing it straight like the pop singers of the past, don't need all this additional show horsing.

