I'm much higher on Davis than most. He's already experienced what most kids go through as freshmen-- learn how to live away from Mom & Dad, learn how to adapt to being a role player rather than big man on campus, etc. Because of that (plus body type and skillset) I expect him to be more adaptable and willing to do whatever the coaches want him to from day one. He appears to me to be the most versatile outside of our clear top 6 dudes, and that's exactly what you want out of the seventh and eighth guys in your rotation. I'm calling it now: barring a slow injury recovery, he's a lock IMO to be in the regular rotation.
As for Nana, I didn't like his game coming out of HS and I haven't seen anything on the floor to change my mind. Thor I have no opinion on, since I couldn't make heads or tales of his HS tape and I never saw him get meaningful minutes last year. Harris' chance at decent minutes is contingent on what the coaches want to do with Allen. If Allen is allowed to settle in exclusively as a SG, then Harris should get at least 5-8 MPG as Glynn's sole backup. But if Allen still plays the combo guard role, then he'll just slide up to the 1 when Glynn rests and I don't see much time for Harris.