Its a tough call this one:
The Norton fight was probably his toughest win.
The first Shavers fight was possibly his finest display of sheer boxing skill. This might also be very under appreciated when considering Shavers's excellent performances against Ali and Norton.
The Cooney match was also a very good performance, but poor Gerry might have been a touch over-rated based on his recent diet of near shot has beens.
A controversial choice might be the victory over Tim Witherspoon. Terrible Tim might have been relatively inexperienced, but he was clearly well prepared and very much in his prime. 'That' Witherspoon may well have beaten Norton, Cooney and Shavers too.