1. Solich - even if the program took a downturn under his watch, and a noticeable one, he is still the only coach since Osborne to pilot the program to a national title appearance. He also won a conference title and helped cultivate a Heisman trophy winner. He may have ridden the success of Osborne's recruits, but, his accomplishments are still better than the rest.
2. Pelini - never lost few than 9 games, helped coach one of the best defenses and best college football players in recent years and had few off the field problems. And for as much as it sucked not being able to consistently win the big one, I'll admit that he sure made games interesting sometimes.
3. Callahan - he (so far) lasted longer than Riley and made it to a Big 12 title game, even if he didn't win it.
4. Riley - I don't think any one in good conscience can put him above any of the other other coaches, yet. A 6-7 season with uncertainty moving forward is enough to keep him under the rest.