You exclude Charles because he never won or defended the title ,fair enough ,yet you have O Brien at no 7.O Brien won the title from a 42 year old Fitz ,and never defended it,plus he was kod twice by the Middleweight King Ketchel.
Conn would be held in much more high regard if he'd either won his first fight with Louis, or at least defended his own title a few more times. His failure to close the show against Louis and the interruption of the war years hindered what could've been one of the very best legacies in LHW history. However, Conn does get my vote as the greatest super-middleweight of all time.
Conn beat a Champion in Bettina twice ,ditto lesnevich ,not bad really he went after the bigger purses at Heavy.You are right about Super middle he has an excellent record there.