Bill O'Brien would be my #1 attainable target. O'Brien's offensive scheme would give Nebraska its first true offensive identity since the middle of the Pelini era. Our quarterback play would be the best its been since Joe Ganz was here. We would stop hemorrhaging signal caller turnovers like we have the past 13 or 14 years. Receivers would be coached extremely well, with a lot of emphasis on teaching how to exploit defenses. O'Brien would recruit just as well as Frost, perhaps even a tick better.
There are some downsides to O'Brien. He is very prickly (although nothing near as abrasive as Bo was). I'm not sure he'd be the guy who would stay 6+ years if he got us rolling.