I expect Ray to stay in Boston. I think Boston will be his first option and will re-sign so long as Danny makes a competitive offer.
The stability of it on and off the court (for him and his family), having been apart of a great team and enjoyed great success here which I think will have a big pull, staying with the guys who he fought alongside and won a Championship with, a roster that can still be a title contender if Danny brings the band back for (at least) one more run.
I think it'll be difficult for Ray to walk away from that and that he'll only do so if Danny slights him. So, that brings us to the other option, if Danny doesn't make a competitive offer then I think Ray will look elsewhere.
But Danny seems to really value Ray quite highly so I'd be very surprised if he didn't make Ray a good offer.