Probably Solo Ball, but Stewart not far behind.
I expect Singare to be behind Samson for backup C minutes.
Ross is a dark horse if his shooting is better than advertised, but he may not be physically ready to contribute big minutes off the bench.
I think I haver higher expectations for Stewart than others. He looks physically ready for this level, although he may lack some quickness and that could limit the role he can fill as it would be tough to play him at the 3 with Karaban at the 4. I think his shooting is a plus, and he could be a primary backup for Karaban, but typically when AK sat we moved AJax to the 4 and went 4 out. Anticipating we may do the same next year, that leaves Solo.
Ball can be a plus defender, which will help him see minutes early. He also has a slashing skillset most of our other guards/wings don't (save AJax).
If Stewart can be an effective AK backup and Solo ends up the 5th or 6th guard behind Newton, Castle, AJax, Timberlake, and Diarra, then I could see it being Stewart. But I think it's more likely Solo is one of AJax's primary backups (particularly if Jackson gets in early foul trouble) and is in the mix at guard/wing, thereby seeing a consistent 10-15 a game.