RJ Barrett has a very high ceiling, but I could see him struggling a couple years before becoming a good contributor. He doesn't have the best habits, which I will assume get fixed in the NBA, but you never know.
Reddish should at least be a decent 3 and D guy with potential to be special in that role, but he is so incredibly weak around the rim and you forget he's even on the floor for long stretches. He just doesn't seem like he'll be a star.
Zion should be able to contribute to winning right away, he should be a star, and likely will be a superstar, with the potential to be the best player in the league.
All 3 of them have concerning FT %, which could indicate they never become very good 3p shooters, which would be pretty detrimental to RJB and CR's progress. They need to be good at that, unlike Zion, who can get away with being mediocre at that.