Well for starters AJ was a hardnosed player, where as Reggie was a flashy player. AJ's background is much more based on D than Reggie's was. He played on the Spurs, he learned from Pop, during his 3 years his team always played good D, Reggie's never did and Natt was an instafailure from day one. Sorry but it's not close.
Those are good points-- it does seem that Avery Johnson has the pedigree of a guy who could teach solid fundamentals and defense. However, being a good player does not equate to being a good coach. There are endless examples of this. Some people have it, some don't. If I'm building a hard-nosed defensive squad I would hire Avery Johnson to be my PG before I hired Reggie Theus or (ha!) Kenny Natt. But that doesn't necessarily mean he would be a better coach. I will say that absolutely I would hire Avery Johnson as my coach before I hired Kenny Natt or Reggie Theus. If that's the pool, you go with the guy who is relatively more experienced. But I don't think three years of coaching experience and getting fired by the same team you won a coach of the year award for the previous year makes you a slam dunk candidate to lead our team out of the dark ages. He's a candidate. He's under consideration. But he's not the only candidate.