This is a good question. Lewis will generally get more credit for his win but I think it's a tough one.
I think one of the biggest factors here is the manner of the stoppage. Against Lennox, Vitali was desperate to go on despite his face being in pieces while against Byrd he just quit himself (for whatever reason). Because of that I edge slightly towards Byrd's win being slightly better. But it's very close and there's not much between them. Both were questionable "wins" IMO.
I think one of the biggest factors here is the manner of the stoppage. Against Lennox, Vitali was desperate to go on despite his face being in pieces while against Byrd he just quit himself (for whatever reason). Because of that I edge slightly towards Byrd's win being slightly better. But it's very close and there's not much between them. Both were questionable "wins" IMO.