OK, I agree with what many others have said--Cameron is better than Clay but the concussions scare us.
Here is why, if healthy, Cameron is better IMHO.
Cameron produced with an inferior offense. He runs seam routes better and has better routes and a better feel for soft spots in the zone than Clay. Cameron is not as strong after the catch but, but gets open much more reliably. He has the speed and size to make the tough middle seam catch in traffic, whereas Clay was too short and not precise in his routes leading to too high a chance for interception to even call that play most of the time. Cameron has a much bigger catch radius and is a superior red zone target.
With Tannehill throwing him the ball and in Lazor's offense, a healthy Cameron could be the 3rd best TE in the league after Gronk and Graham. If his injuries shut him down, we just need a contract that frees the capspace.
Neither Clay nor Cameron are good blockers, but as a move TE Cameron offers a lot more to an offense. We haven't really seen it yet, but Lazor's offense features a good TE. If at least one of them could block I'd be OK with going more 2 TE sets.