Tough call. To date, none of them have justified their draft position, which means unless they improve, they are overpaid.
Elliott has, by far, the most potential. Unfortunately, he also has the most potential to get injured. And while he's not the highlight film dunker Elliott is, I see Will Barton filling a similar role for a lot less money.
At this point, I think I'd pass on extending all of them and see how they preform this season before committing any more guaranteed money to any of them. Yeah, you risk losing them if they blow up and get offered more money elsewhere, but that seems like pretty small risk.
BNM