It's LeBron.
We've seen them one the court together and at no point did anyone walk away thinking that Curry was the better player. He just always had the better talent around him.
This is such an elementary way of looking at it.
Steph cultivated the culture/system that led to a dynasty and the players that played alongside him became the best versions of themselves. Does Draymond become the player he does if he plays alongside Bron for his entire career, or would he have likely been traded long ago for a
shooter? Does Wiggins turn into the same player if he played alongside Bron? How many players have played alongside Steph and become better as a result? How many players have benefitted from Steph being the most selfless superstar of the modern era? How many players have benefitted from having more easy scoring opportunities as a result from his gravity and off-ball movement?
Nobody should hold it against Bron that he wanted to maximize his chances of winning by hopping from team to team, but there's a reason why he hasn't been able to create the same environment that Steph has.