For a center, I think Milutinov is the better prospect, but Cady is a guy you could bring in if you think Davis isn't coming back next year for example.
Frankly, I was looking up the RFA for next summer and there is an apparent consensus both Kyle and Davis are staying in the Spurs, mostly bc they haven't priced themselves out and the market for RFA is going to be really tough on them. It's rickety to try to predict the summer IMO, but the casuals tend to think they stay put. However, if they were not going to stay put, then Cady comes into play.