Not sure if this was mentioned here, but it should be given that Sickels IMO is the best in the biz at the prospect game. He released his Top 150 prospects as of May 1, and the Reds look like this:
Not much to argue with here, although I'd probably replace Hamilton with Yorman Rodriguez (now that Hamilton is graduated), and Ervin with Michael Lorenzen if he can continue to perform and improve his K rates in AA. 73 and 80 might be a bit high for those guys, as I think somewhere in the 90s is more realistic. Ditto for Lively, who should certainly garner top 100 consideration given his other-worldly start to the season. Ervin has fallen off the map with an abysmal start to the season - probably unlikely to deserve top 100 and possibly even top 150 consideration, unless he picks up significantly in the next month or two. Travieso is the one other guy I should mention here, he probably currently deserves to get mention in the 100-150 range.