Jabari, since he’s yet to show all of his tools on offense due to lack of consistency in playing time (injuries), role and just getting the ball in the right spots. Now that he’s paid snd focusing on ball handling and putting it on the floor I think he’s the most likely to take the biggest leap. Amen already made that jump last year. He won’t be vastly improved and I could see more focus on him from opponents so let’s see how he handles it. Jabari will also benefit greatly from having KD.
I think Jabari will show a lot of growth, but my bet is on Amen cuz he will get to start and build on the momentum he got last year. With KD, FVV and a stretch PF in Jabari/Tari/DFS I think there's gonna be improved spacing on the team and that will allow Amen to run wild.
I think the board is sleeping on Tari Eason. He's had a full offseason, so I expect him to make a noticeable jump in skill and decision-making. In my mind, Amen has already made the jump. He's got it. The future is his. Alpi appears to have worked out his shooting if he can keep his body from getting beaten up.