His criteria for what defines a "prospect" is a player with fewer than 50 career NHL games played or fewer than 25 NHL games played during the prior season and are under 26-years old. He also leaves off players who are signed in the KHL past age 22 (i.e. Kirill Petrov).
Here's his list of the top 15:
1. Ryan Strome, Center (2011 draft)
2. Ryan Pulock, Defense (2013)
3. Griffin Reinhart, Defense (2012)
4. Brock Nelson, Center (2010)
5. Calvin de Haan, Defense (2009)
6. Matt Donovan, Defense (2008)
7. Ville Pokka, Defense (2012)
8. Kirill Kabanov, Right Wing (2010)
9. Johan Sundstron, Center (2011)
10. Scott Mayfield, Defense (2011)
11. Anders Lee, Center (2009)
12. Taylor Cammarata, Left Wing (2013)
13. Adam Pelech, Defense (2012)
14. Andrei Pedan, Defense (2011)
15. Alan Quine, Left Wing (2013)
The surprise for me is how high de Haan is ranked after all the setbacks; he's still ahead of Donovan, Pokka and Mayfield. He only trails the two high-end defensive prospects the Islanders have. Also of note is that there are no goalies on this list, although Pronman himself admits he gives goalies a low ranking in his ratings (explanation why here).
According to Pronman, the two players at the top are the ones that he projects could be impact players. He calls Strome "a top line forward, and maybe even a potential star" and projects that this year's first rounder, Pulock, "could be a top-pair defender." Reinhart is the only other player that he projects could be more than a second line or second pairing player. But don't let that get you down. Keep in mind that he still thinks the Islanders prospect pool is the second best in the NHL.