Langford or Greb, then Armstrong or Charles. If it's just outright bestest you're looking for though, its totally Duran.
talented unreal boxer standouts for me are joe louis, roy jones, floyd $ mayweather, bernard hopkins and wat we knew of joe gans and charley burley. im a tommy loughran fan once he adapted his style too, and cant help but appreciate roberto duran, jack dempsey, and julio cesar chavez (shame bout that kid of his tho...)
Hard to debate that stat. The literal toughest guy to ever lace them up is likely harry greb. One eye, fought every 2 weeks in the ring, got drunk after an official fight and then fought guys at the bar for money.
Got into a fight with Mickey Walker in the street after their fight, too. Beat him a second time, apparently.