First base looks to be quite a bit rosier for the Cubs than catcher does. They Cubs have a budding star at the top and some very intriguing options at the bottom.
The league average 1B last year had a wOBA of .337.
Anthony Rizzo had himself a nice little half-season last year. I'd like to see some more walks, but I'm happy with his contact numbers (generally) and his power has developed nicely. He's a cheap, good, middle-of-the-order type of hitter. He is swing-happy, but as long as he can put a bat on the ball who cares? He also crushes off-speed offerings, so he's going to get hittable pitches. Hooray!
Greg, of Rohan is probably a Quad-A guy. He put up solid numbers last year, but it was his first taste of AAA at 26. I wouldn't hate having him as the backup 1B (and he bats righty, so he'd presumably platoon well with Rizzo), but his numbers indicate he's eminently replaceable. Blake Lalli was the primary backup to Rizzo but he's gone now.
Justin Bour had a nice little season. He's still young enough to maybe be on the periphery (he'll be 25 in AAA this season) and he's shown ability at every level in his career. He could be a solid backup as early as late 2013/2014.
Rebel Ridling is org filler at this point. He'll be 27, in AA, hitting league average, next year. Going to go ahead and pass on him. The first time I ever heard of Richard Jones was research for this article. It's the last time you'll ever hear of him, too: he's coming to a Home Depot near you.
UPDATE: Both of these guys were released. MLBTR has nothing on either of them, apparently they are THAT useless. Thanks to OV Platinum Member Chet Masterson for the tip.
Paul Hoilman is too old to be in A without absolutely dominating. He's a 2011 draftee, so the book isn't completely written on him, but he better get good in a hurry: 473 PA of .718 OPS ball from 1B is not so good. Ryan Cuneo was released by the Cubs when he couldn't hit himself out of Peoria. He will not be missed. Jacob Rogers brought the thunder in his first taste of professional action, putting up a .999 OPS in Arizona and a .913 OPS in Peoria. He takes a ton of walks. He should be a fast mover in the system; he's already 22 so he should have a pretty firm grasp of minor-league quality hurlers. He's a fringey-prospect but someone I'll be keeping an eye on.
Call me crazy, but I'm not sure Daniel Vogelbach isn't the 2nd best prospect in the Cubs organization (Baez is one with a bullet). Vogelbach has a few years to get in shape to play first (and I've heard the first whispers that he could even end up at left field if he improves as rapidly as he has). I don't care about getting him to the outfield; if he plays at first, he could be a special hitting prospect. Using this handy tool (and assuming A numbers, since A- doesn't fit in there), Vogelbach was already better than Vitters was last year (dying laughing). He's got very good plate discipline. He makes contact. He's got legitimate plus-plus power, and that includes doubles power (he hit 21 in 283 PA last season). He's got one of the best 5 or 10 bats in all of the minor leagues, and the Cubs are lucky to have him (and 1B prospects are slightly thin at the moment, anyway). Rock Shoulders hit very well in his limited time, too. He's not a high-quality prospect, but he could put himself there with a nice season in 2013.
Trevor Gretzky sure looks like a bust. He's still only 19, but he has absolutely no power. He plays 1B and LF, neither all that well, and he's tall but not strong. He'll get his chances (7th round, 2011), but I'm not holding my breath.
All in all, this isn't a bad bunch of players. I'm not sure where I'd put these guys in a list of our top prospects, but Vogelbach is certainly one, with Bour and Shoulders getting some fringe-consideration at the bottom of the top 30.
AA: YOUR NAME HERE
A: Vogelbach (I'd love to see him start the season at A+ or even AA, but I'll take A+)/Hoilman
I don't like keeping Shoulders at A-, but I do think it's where he'll start the season.