In my mind, the great triumvirate of the soprano saxophone is Bechet-Lacy-Parker. (Evan, that is.) Convincing arguments could be made for the significance of Coltrane-Braxton-Liebman's contributions to the horn, but they tend to strike me less as innovators and more as superlative practitioners.
I'm leaving out a lot of other important players on this horn, though. Who do you like on the soprano?