Bentil of Hunter
Hunter probably makes more sense to the Celtics since he has a history with Brad Stevens, has a high Basketball IQ, is a solid passer, has shown that he can bother people with his length on defense, and has a history as a top shelf scorer. Probably has the versatility to play three positions (PG, SG, SF) in stretches if he bulks up a bit. That type of versatility plays right into Brad Steven's system, and Hunter has only been here for a year so it feels a little unfair to give up on him so soon.
Bentil would be my personal choice - don't know why, I just see a big with a legit NBA body, NBA physicality, and a nice shooting touch. I think those are nice things to have in this league.
I'd be pretty content with either honestly. Would be very disappointed if it's Young, but I doubt Danny is forgiving enough to look past three seasons of complete uselessness.