I wouldn't do a thing with JD. As great as he is, I'm not convinced his market will be overly robust when he's two years older, two years more a DH.I might be crazy but I'd rather prioritize Betts, JD, and even JBJ over Xander for an extension. I don't think Xander signs anything team friendly (Boras) and I think he's least likely to bring back value over what would easily be a $100M++ contract. Loopy swing, injuries, average defense. Focus #1 on Betts and convincing JD to forgo is opt-out in exchange for tacking on years. Lock down an all-time great defensive CF for reasonable money.
I think Xander will be a very interesting situation in that I'm not sure what his market will be. There are a lot of great shortstops around the league.