These are my rankings based on hitting ability and positional value. I am only including guys who spent the majority of their time at full season A ball or above and haven't yet reached the majors. For what it is worth, here it goes:

1) Jonathan Singleton (1B), DOB 9-91. Good, young, all-around hitter.
2) Jonathan Villar (SS), 5-91. 43 extra base hits almost makes you forget about the 156 K's.
3) Domingo Santana (OF), 8-92. .287/.362/.471 slash line very promising.
4) Delino DeShields, Jr. (2B), 8-92. Not as many positives as Villar to offset low batting average (.220) and strikeouts.
5) Kody Hinze (1B), 7-87. I believe in the bat - patience and power combo. He was not overmatched at AA (46 K's in 199 AB's), even though his production fell some (.780 OPS).
6) Chris Wallace (C), 4-88. Rough transition to AA, but had moved from rookie league to low A to single A to AA in just over a year's time. 20 HR's - that's a good year for a catcher.
7) Austin Wates (CF/OF), 9-88. Solid all around, but didn't distance himself from other hitters in high A ball (105 OPS+). When I squint I see Jason Bourgeois. I expect that some of you would have him several slots higher.
8) Jiovanni Mier (SS), 8-90. Similar to Villar and DeShields, he needs to reduce K's and increase his batting average (.245 at Lexington, .233 at Lancaster).
9) Telvin Nash (OF/1B), 2-91. Great power (14 HR in 268 AB at Lexington), but the strikeouts are scary (103 K's). Could move him up a few slots, but doesn't offer much defensive value.
10) Adam Bailey (OF), 3-88. Contact hitter who needs to take more walks, but accumulated 24 HR's over three levels.
11) Jonathan Meyer (3B), 11-90. Steady improvement each year, and still young. I'm concerned about the bat though - possibility of a bit of a mirage from Cal League environment. .264/.343/.399.
12) Roberto Pena (C), 6-92. Overmatched at the plate this year (.576 OPS), but he is young. He'll need to show some strides next year though. I hope to see him repeat Lexington.
13) Jacob Goebbert (OF), 9-87. Performance didn't change much as he advanced from A+ to AAA. He was steady throughout the year. 12 total home runs is a bit underwhelming though.
14) Mike Kvasnicka (3B), 12-88. Still some faint hope that he will add power eventually. Only 4 HR's this year in 484 AB's.
15) Brandon Wikoff (2B/SS/3B), 4-88. Maybe a stretch here, but no one else was screaming to get on the list. Up and down season ended on a down note with a few games at AAA (6 K's in 15 plate appearances - very un-Wikoff-like!). Positional value added came into play here some, as did a .398 OBP at Corpus.

Others considered: Jay Austin, Emilio King, Brandon Barnes, David Flores, Ben Heath, J. Thompson