Pacquiao's wins stand out more (Oscar, Hatton, Cotto, Barrera, Morales, Marquez, Ledwaba, Diaz, Mosley, Bradley, Clottey, Margarito, Broner, Thurman, etc) across multiple decades and divisions where Pacquiao is always the smaller shorter guy.
Ray Robinson's best wins (Lamotta, Angott, Servo, Berger, Turpin, Zivic, Olson, Fulmer, Gavilan, Basilio, past prime Armstrong, Janazzo, Wade etc) were guys with barely any film footage and most people haven't even heard of them or seen them fight.