I don't really see Snoke caring much for Rey other than wanting her dead, from what he said in TFA, because she's a huge thread, force wise. I think Snoke is more connected to Kylo and Luke's story, because obviously Luke failed Kylo at some point and Snoke slipped in and pushed him to the dark side.
I really hope the final battle with Snoke is with him and Luke, not Rey (or even Kylo of he turns good again). I think Snoke is the big guns and our big guns = Luke