no-one.  Simple harmonization contest has no winner.   I’ll post soon on how to analyze the intonation in the contest fragment: but the essential piece is this:  after a tonic, Do, the Re following has to be either high tuned or low.  If high tuned, it is harmonized by a dominant form; if low tuned, by the supertonic acting as subdominant.   The fourth note is the leading tone, the only acceptable minor third between 2 and 7 is a large minor third, thus the  third note, that second, MUST be tuned high, and over a dominant harmony.   Placing a ii chord on the first beat of the second measure CAN’T work; it must be a V (or, if I had allowed it, a vii o6) .  With the requirement that the chord change every half note, then the only acceptable harmonization of the leading tone left is the iii chord, either root or first position.