I voted for Sanford. He has soft hands, a decent shot (which will improve as he adds strength), skates well, passes well, has very good offensive sense, and seems to know how to find the open places. He needs to add lots of strength and muscle weight, and learn how to use body leverage better, and adjust to the added bulk. He will likely do all that. IF he does a good job of all that, he can be an average 2nd line winger, and if he excels in that, maybe he could even become an average 2nd Line NHL centre.
Musil is probably a certainty to make at least 4th Line NHL forward, and possibly 3rd Liner. If he improves on his current trajectory, he could become a 4th line NHL centre, who can move up to 3rd Line. He's probably closer to reaching all those than Sanford, at this point. But sanford's high ceiling gives him the nod.
Toropchenko should be up there, as he seems to have a reasonably high ceiling. But, he's a lot farther away than Sanford, at this point.