Wililngham is the worst, hands down. Lazy coach, lazy recruiter, and kept an inept staff.
A lot of people seem to forget that the 2004 and 2005 classes (or at least the part of the 2005 class that was committed) were two of the worst recruiting classes of all time at ND.
When 2007 rolled around, there was virtually no senior or junior depth. That will happen when you fill your classes with players the likes of Tregg Duerson, etc., and we definitely got killed by teams who did have senior and junior depth, and even Nick Saban wouldn't have been able to field a .500 team with that roster.
Charlie Weis had his faults, and looking back on things, wasn't ready to run a collegiate program, since you can't treat college athletes like professional athletes.
He did help turn the program around. Instead of settling for 2 and 3 star talent we were finally getting players who could hold their own against the powerhouses again. I do believe that had he been given one more chance, we could have had a 9 or 10 win season in 2010 (assuming Clausen had stayed).
His biggest mistake was thinking that Jon Tenuta could actually run a defense... When you jailbreak blitz every down with players who aren't the right fit, well, the results spoke quite loudly.