Football is too much a team sport to compare players any position in a vacuum over history. Especially with changes in the offensive scheme, playcallers, complimentary players, competition, etc.
With that said, unfortunately, his legacy comes down to coulda, woulda, shoulda. In the end, no nattys, no gold pants, no playoff wins, and no B1G titles is never going to rank well at OSU...and two trips to NYC don't really help that much.
I know some will say the defense let him down. However, it's a team sport and whether its a bad defense, a weaker WR corps, a poorer complimentary running attack, or coaching holding you back doesn't rally matter.
If you're asking who I'd want (assuming all are in their best season and only recent QBs) to lead the bucks for a year, I'd take (in this order): Fields, JT, Smith, Stroud, Haskins, Pryor. Pryor was maybe the best athlete (close call with Fields), but never developed the passing skills probably in-part due to coaching and scheme. Miller belongs in that latter camp too. Incredible athlete, decent passer.