Anyway, the top of the farm is stacked, and here is some notes from Cubs Den (with some info on subscription-only stuff):
Cubs #12 farm system in baseball (still room for improvement, but Dewey seems to think that it is bad, and I agree with this ranking). Top 10 are shown online in another article I found, here's the order: 1. STL, 2. SEA, 3. MIA, 4. TEX, 5. BOS, 6. TB, 7. MIN, 8. PIT, 9. ARI, 10. HOU. Most agree that our farm doesn't have enough impact players, but our main impact players that do exist are really damn good (see below), and we have a ton of depth.
Callis said that he'd currently rank Baez #11 in baseball, and that Soler, Almora, and Baez are almost interchangeable in order, so expect them all in the teens or twenties, thirties at the absolute lowest.
Rest of Cubs Den analysis:
http://www.chicagonow.com/cubs-den/2013/01/baseball-america-cubs-top-10-prospects/