Stones is a top player imo and will benefit from a good midfield in front of him. Get him and Smalling playing together as they'll then be there for years.
I don't think Wilshere has ever been fresh as a daisy in his life. Maybe a daisy that lives downwind from a cigarette factory of course... Personally I still feel Stones' form this season has been more due to Martinez mismanaging him and constantly praising him for trying risky passes that don't come off. With Roy being a bit more conservative, and with a better CB partner and DM cover, I think he could shine. And I also don't see Cahill as any less of a risk tbh.