Four pitching prospects

In a very deep dynasty league, I'm looking at four pitching prospects and am having difficulty deciding which one of them I should pick up. Some of them you might already be following; others you might not be. Here are my thoughts about them, and I'd like to hear yours.

Wily Peralta is the most dominating of the four. Before his Tommy Johns surgery two years ago, he touched 98 mph with a hard-breaking slider. Since he's come back, he's been very productive, though BA thought he'd end up in the bullpen. John referred to him as a high-upside arm. So far this year, at age 20 in A ball, he's struck out 77 while walking only 17 in 60 IP, for an FIP of 2.31, half a point better than the #2 person in the Midwest League. The issues with him, though, is that he's averaged only 4 IP per start, often pulled out after only 3 or so innings, and may end up in the bullpen. I also haven't been able to find any current accounts of his stuff.

J.J. Hoover is another guy with good stuff and excellent results in A ball. John named him as one of his sleepers. He has a low 90s fastball, and potentially 3 other average or better pitches. At 21 in A ball, he has a K:BB ratio of 67:9 in 61.2 IP and an FIP of 3.21. With the exception of a few early starts, he's pitched 5 or more innings in almost all of his starts, and projects to be a starter.

Zeke Spruill is the only one of these pitchers who John gave a B- too (the others are C+ or lower). His fastball is also in the low 90s with movement and projection, and 3 other pitches that have potential, has good control, yet he's had difficulty striking out many batters in A ball at 19. That being said, his other components have been positive (only 12 walks in 70.1 IP, and a FIP of 3.63).

Scott Diamond has already had success in AA, despite being seen as having less potential than the other 3. At age 22 in AA, his 63:33 K:BB in 81 IP is respectable, as is his 3.58 FIP. He's a lefty with a fastball in the upper 80s and a plus curveball, along with a knack of getting groundballs. It's uncertain, though, if his stuff is good enough to carry him into the majors.

So, what are your thoughts about these four pitching prospects? Who am I under-rating, over-rating? Who is the real deal and who just isn't? Finally, if you could have only one, who would you take (if any of them)?