Factor in talent, potential and overall success / records, who is the greatest player ever above 6 foot 3 inches in height out of all the giant tall players?
Becker is the one wurh best career, by far. Probably talentwise close to Safin, how else could he have such a career. However, you said above 6 foot 3 inches, and i think Becker was exactly 6 foot 3 inches.
I would hardly call 6'3 a "giant." In any case, here's your answer (Monfils isn't in the discussion and having stood next to Boris several times, he's closer to 6'2):