Which coaching vacancy is the best?

Not sure if I agree with you here...Their defense is terrible no matter what coach comes in with their game plan, their line might need an overhaul.  Same with their offensive line which was lit up last year mostly due to injury but they weren't that good before that.  Julio Jones is an excellent receiver but often injured, and Roddy White and Steven Jackson are getting long in the tooth so I am not sure how this is "easily" the best place to go for a coach. 

I struggle to see how the current Bears job is better than the current Jets job. The entire Bears roster is due for a slash and burn.

The Oakland job is strictly better( in some eyes) on the anticipation that Derrick Carr is legit. He had a nice rookie year, but is he a sure fire 10 year starter?

Nothing is ever a sure thing but, as of now, I'd say the Oakland QB situation is much better than the Jets, Buffalo and Chicago (especially if Cutler trade rumors are valid).

We've seen average/bad coaches win with an excellent QB. You rarely see even good coaches winning with bad QBs. The common thread almost every year in the playoffs is that those 12 teams have QBs who are in the Top third to half of the league. I could make a case that the Atlanta, Oakland, and SF jobs are the most attractive from a "close to being able to contend" standpoint. Because of Atlanta's division that's almost a slam dunk as the #1 job in my opinion. And those are two of the 3 key questions I'd ask if I were a coaching candidate, QB and division.....

1. Who is my QB? (Young franchise type guy or major uncertainty?)
2. What kind of division do I play in? (Do you want to face Aaron Rodgers and Matthew Stafford 4 times each year? etc.)
3. What is the salary cap, draft pick situation? (Can I reload quickly?)

rex the best candidate?  what happened is pretty amusing when you think about it.  one thing i would ask the casserly/wolf brain trust is if they objectively assessed rex as a candidate for the jets job.  we all know what rex's limitations were but many of them could have been fixed with a decent gm who knew how to supply the players a rex team needs and could keep an eye on rex's players coach attitude.  imo rex was too much of a players coach and didn't like to hold the players accountable all that often.  hence the missed team meetings by geno and pryor.  and rex sould've tried other players at corner when it was apparent that allen wasn't doing the job.  (he finally did bring up williams but it was 6 games too late).  i also think he was forced to start geno by idzik who basically wanted to find a russell wilson clone.

The coaching vacancy that's the best is the New York Jets.  Why, because the head coach of the Jets that wins the Super Bowl will become iconic.  You make it big in New York, you'll go world wide.