who had more success as singles, Travis Parrott or Pierre-Hugues Herbert
Pierre-Hugues Herbert: Pierre-Hugues Herbert (] ; born 18 March 1991) is a French professional tennis player. Pierre-Hugues Herbert:  In singles he has reached one ATP career final (at the 2015 Winston-Salem Open), and achieved his career high singles ranking of World No. 64 on 14 August 2017.
i don't know