Who would win?
Senior PGA. Some of the guys on that tour could be/are competitive on the regular tour. If the senior men had played Cherry Hills last week (site of the U.S. Womens Open), I’d guess someone would shoot -10 or better, while the Woman’s winner finished +2. The course is just too short these days.
Peter Jacobsen just recently finished tied for 15th in the U.S. Open and Craig Stadler has been competitive on the regular tour as well. I think he won a tournament on the regular tour after he turned 50. Just looked and saw that Stadler has a ninth and a fourteeth place finish this year on the PGA tour, and made the cut at the Masters.
Maybe if you put the age line at 60 it might be competitive.