There really is no comparison between Gordon and Longoria, not because Longoria is bad, but because Gordon is so good. HOWEVER, Longoria could very well be in line for a shift to 2B, which would make his power and overall hitting ability all the more valuable. Gordon's ML ready and Longoria still has a little ways to go.
Cain has unbelievable stuff, rough control, and ace ability. By ace ability, I mean top five pitcher in baseball. Gallardo's stuff is certainly good, but none of his pitches are off the charts. He throws four of them, has good control, and projects to be a #2 starter, possibly a "weak" #1.
Cameron Maybin is probably the best OF prospect in baseball. He has an advanced approach at the plate, though his contact skills need a lot of work. He walked 50 times in his full season debut, which is very encouraging, but struck out 110+, which isn't very impressing at Low-A. His power and speed combination and potential make a scout aroused; he could be Alfonso Soriano with Gold Glove D in CF, a batting average, and an ability to take a walk. Milledge is... I don't know. I don't care for him much. The tools are there but he seems like a guy who will take a few years before they click. Still, his potential is not near Maybin's and they both seem about an equal distance away from actually being ready (exaggeration - Milledge is almost ready, but he won't contribute much).
From a baseball standpoint, Hermida is very valuable. Excellent approach at the plate, great defense, good arm, works hard, has leadership ability, but talking fantasy, I'd have to go with Bruce. Hermida will probably be a .300-20+ guy with a few steals and a very good OBP. Bruce could be a 30-30 guy, though it is likely his speed will suffer as he adds on more muscle (and power). Like most other young hitters, he Ks a good amount, but he is still young and has a pretty good approach at the plate.
Cole Hamels is filthy and could truly be an ace. However, staying healthy has proved to be a HUGE problem for Hamels. Kershaw is actually similar to Hamels but four years younger. Kershaw and Hamels both stand at 6'3", but Kershaw has a much better build at 220 compared to Hamels' 175. Kershaw has a great fastball that tops at 96 (and will probably get even better as he matures further), a plus curveball, and a change that he just started throwing consistently in the pros because he did not need to use it in high school. A big plus about Kershaw compared to 99.9% of the other power pitchers in the Minors is his absurd control; in his brief time as a professional, he walked five batters in 37 innings, and it is said he can hit the catcher's glove with pinpoint accuracy with all three of his pitches. He also knows how to pitch; he really is mature beyond his age. However, he's just going to be 19 at A-ball entering '07, and though his ceiling may be slightly above Hamels', he's got a long, long ways to go - Hamels wins this one.
I don't know who I would compare Miller with, but he's a 6'6" lefty with a high-90s fastball and disgusting slider. He has great starter potential.
Lincecum is disgusting. People worry about his size and mechanics (which are perfect), but he has done everything in his power to prove he's healthy and he looks good. Could and should be up at some point this season, probably as a starter, but if the Giants need help filling Benitez' shoes, Lincecum could do a fine job closing for the Giants this season. Reminds a lot of people of Roy Oswalt.