Lonzo will be better than Fultz
Why I can't predict the future, theres things about Balls game that will hurt him in the NBA.
Fultz averaged 2 less assists but almost ten more points than Ball, which means he contributed more to the team on the offensive end. At least points wise. And Fultz had horrible teammates compared to Ball, so that means he was getting his teammates the best possible opportunities to score. Futlz also runs the pick and roll, which is the NBA.
Ball who is right handed, can't go right because of how he brings the ball around from left to right. They count on him being bigger than most PG's to get the shot off, but in the NBA that wont always be the case. Smart will have fun with the kid. Ball relies on DEEP(bad) 3 ball shots for a lot of his shots because of that. And since he can't shoot a mid range, the staple of the NBA pick and roll will hurt him a lot. So he's going to have to get to the hoop more, which will be easier in college than the pros.
Also Balls rookie season is going to be rough. Thanks to his dads mouth and the dumb shoe thing, it's been rumored some of the pros haven't taken a liking to it like some have, and will go all out on the kid when they match up. Hopefully the kid has his dads confidence, because it could get broke quick.