Very difficult to quantify this. But I'll share some insight:
-I feel Sinner is unique in that he's the greatest tall player of all time (6'4").
(Imagine if Soderling had stamina, footwork, defense etc. Imagine if Del Potro had longevity and consistency. This is what you're getting w/ Sinner).
-Sinner gives you an instant idea of what a tall skilled player in the (6'4"-6'6" range) can do when almost EVERYTHING clicks in their game.
-Carlos has the DNA of the Big 3 for obvious reasons, except he's probably not as accurate as the Big 3 (particularly Nadal), but maybe he'll get there very soon
after that monster US Open run that showed discipline and hunger to improve his weaknesses (e.g. serve %, ROS depth).
-Carlos having a two-hander is the closest we get to a two-hander Roger Federer,
Granted, some will argue that Joao Fonesca will be that guy in the future because his forehand resembles Federer more among other possible factors
(I don't know, but I feel Carlos in terms of sheer variety is closer to Federer)*