To make this easier on me, lets line it up
15/7/10/18/17/10 7/6/3/4 5/7
12/7/8/12/11/10 3/4/4/4 7/9
14/7/8/10/9/4 5/1/6/7 4/3
Prospect #3's value to you is as an immediate sell. He cant play PG because his passing is bad. He cant play SG/SF in most offenses because he will fail bad against any team who actually builds their SG's and SF's properly. By properly, lets talk middle of the road D.III teams in the US, which are roughly 12k ranked worldwide. These teams typically have SG's that have 6-7 IS minimum, and i'd guess that they have 9-10 IS minimum at SF. A 1 ID will get beaten up on most any inside shots, and there is enough of a percentage to make it bad for him.
Prospect #1's value is mediocre as a PG because of low passing, but pretty good as a SG right here and now. If he gets better IS and ID, he could move towards a decent SF player.
Prospect #2's value is as a PG long term assuming you can get him in for a lot of passing. I think he's too late in the game to convert into as good of a SG long term.
You probably dont have a true Sf amongst these players, with the first one being the most capable of doing so.