I vote for Bob Hayes.
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If it is hard to fathom the quality of this run, what he achieved in the final is even more staggering. Hayes drew the inside lane for the final, and the last event before the race was the finish of the 20km walk. Remember, this was a cinder track, and the inside lane was so chewed up it had to be raked! Nevertheless, Hayes won in 10.06. He had a 0.19 gap over Cuba's Enrique Figuerola, who equalled the previous best ever auto time of 10.25 (Hary in 1960). Third was Harry Jerome, joint world record holder! This victory margin was not exceeded until Lewis won by 0.20 in 1984. The winning time was ratified as a WR equalling 10.0, which somewhat understated it.
And yet, Hayes greatest performance was yet to come. Running the last leg of the 4x100m, by the time Hayes got the baton, after Paul Drayton, Gerald Ashworth and Richard Stebbins, the USA were some 3-4m down on the field. Hayes, in the words of one observer, "exploded down the track in an eruption of speed never witnessed before or since." He blew past the field in 30-40m and went on to cross the line some 3m clear in a new WR of 39.0. He had taken 6-8m out of some of the finest sprinters in the world. Various times have been given for his last leg, the slowest estimate being 8.9 but most being around 8.6-8.7.