Pancho Gonzalez won around 27 Hardcourt tournament victories, perhaps more. A lot of the surfaces he won tournaments on aren't known so he may have far more. I counted wood as a hard court by the way.
Rod Laver has won around 30 hardcourt tournaments, perhaps a lot more. Again, it's the same as Gonzalez. I counted wood as hard court and many of the surfaces Laver won tournaments were unknown so he could have won far more. There was on Pro Major won on wood.
Ken Rosewall won around 32 hardcourt tournaments, perhaps more. Rosewall won four Pro Majors on wood.
Bill Tilden won probably around 12 hardcourt tournaments.
Jimmy Connors won 45 hardcourt tournaments and 3 majors on hardcourt.