i'd say usyk because he is a boxer first and a puncher second. he would not get into a fire fight with marciano unless he had no choice. backed into a corner type situation. i can see him boxing to a split decision.
Considering that Marciano weighed under 190lbs throughout his entire career, Usyk's entire Cruiserweight career can be considered valid for this analysis. IMO Usyk has had more success as a CW than as a HW so far. Usyk has all the physical advantages except stamina (equal), and punching power. Usyk has the technical advantage as well as the ring IQ. I just think Marciano would be overboxing. Usyk wins on points UD.
Usyk wins this fight without breaking a sweat. His size, footwork and ring IQ are levels above the brute style of Marciano. Different eras and no disrespect to anyone. Usyk probably does the same to Ali and Frazier.
