That's tough yeah, I'd say Russell or Wilt but totally subjective since I haven't seen them play. Maybe Robertson since he was just a gifted freak of nature compared to the other players in the NBA back then, but sama argument here is that I obviously didn't watch him play. There's also arguments to be made that Curry should be higher than guys like Duncan, Shaq or Kobe (but counter-arguments as well, e.g. Shaq is the most dominant player in history imo and Kobe was the face of the NBA for a long time whereas Curry never has been, also greatest Laker of all time imo (and Magic and Shaq agree with that) which is saying something for such a franchise).
It's too damn hard to make a right order in an all-time list. You have to be truly special to be a surefire top-10 pick but imo Curry is that. What he does offensively is mind-blowing and "never even remotely seen something like that before" territory. He blows guys like Ray Allen and Reggie Miller out of the water who were considered among the greatest shooters of all-time before he came around. Couple that to his accolades, achievements, and not only his influence on the NBA game but the game in general, kids in gyms everywhere influenced by him and his game, taking more shots, thinking they can be like Curry, he has a legacy that far surpasses the one like Durant (even though Durant may be a superior basketball force) and no one can convince me otherwise.