I'm sure some of this is a repeat of what has been said already. There are a couple of things to consider when making the decision between c/r-ing and c/c-ing with a set. It has to do with stack sizes, tendencies of our opponent, etc. But usually, I will decide based on the texture of the flop.
For example, if we have 88 in the BB, all fold to the CO who opens for 3x, and we call. Flop comes K84r. Here, I would probably go with c/c-ing, especially if I know villain will barrel on turn, also. The main reasons for this are 1) c/r-ing really gives away the strength of our hand, and 2) it is unlikely that a cheap turn card will beat us. The only time it could beat us is if villain has 99+ and hits a bigger set. Those are long odds, so it's a risk worth taking, usually.
Now consider we have the same hand and the board comes QJ8 two toned. Here, I really want to c/r for a couple of reasons. First, we want to fold out some draws that can beat us (although some players would re-raise their draws, especially the bigger combo draws), whereas before, we pretty much had a lock on the hand. Secondly, our range now can include many semi-bluffs, so we can expect our opponents to call us much lighter than in the previous hand.
Hopefully this helps you figure out which is the more profitable play. I'll mention too that sometimes I c/r in the first scenario, too, if I think villain will call, like if an ace hits, or the villain just goes too far with his hands in general. Balancing also becomes a factor, if you only c/r with sets, or only c/c, or whatever. GL on the tables.