Peraza is a super two player. He will likely make 4.5M next season. He isn't worth anywhere near that unless he starts. He isn't good enough to start everyday at SS on a championship caliber team.For me, this is not an easy choice at all. Peraza has had seasons in which he has hit decently, but he hasn't exactly covered himself with glory offensively during his career -- .275 BA, .313 OBP, .641 OPS. Defensively, he hasn't won a lot of plaudits either, leading the NL in errors at SS in 2018 for example. I'm not sure that giving him the everyday SS job is going to be a move that takes the Reds to the postseason.
Of course, Galvis isn't exactly Barry Larkin either. His comparable stats to Peraza's are less attractive -- .248/.291/.674 -- but not by a whole lot. Defensively is where the difference lies between the two. A look at both players' defensive stats shows a pretty big difference between the two.
I imagine the Reds are going to use both next year. After all, both can play around the infield wherever needed. At trading deadline time, if Galvis hasn't been the answer, then a goodbye is easily done.
If the Reds are going for a championship next season, he should be traded/released/non tendered.