I would select Hinske first b/c he is playing like an elite 3rd baseman right now. He will probably come back to earth, but hopefully Nevin will be back then.
If you don't like rookies, then pick up Valentin. He qualifies at SS as well. He strikes out alot and bats around .250, but he does go yard from time to time.
Tatis is your last option. He just came back from seemingly a lifetime in the infirmary. He had ONE great season, and it is hard to forget. BUT, let him prove he can stay healthy and produce.
So grab the rookie and you shouldn't see any change from the 3b position.