Non-autographed Bob Feller items are probably rarer than signed ones.
He signed a ball for me, at the old Municipal Stadium, in the 1980s and was great. I don’t think he hardly ever turned down signing something, and usually for free unless he was at a show.
However, I vote Pete Rose. He is an autograph machine. As I type this, he’s probably set up at a Vegas hotel/casino signing items at this very moment.