You really have to look at the big picture.
Denver is on the Declined, that D is not the same as the one who carried Manning a few years ago, Anderson is being released to free up cap room, both receivers are 30. They are on the verge of a rebuild with one year to try to win . There is little stability, Vance may be fired before mid season.
The Vikings look good , can pay him but would not be able to keep Diggs,Barr , Kendricks and others next season. Keenum makes more sense for them, he played great and has chemistry with the rest of the team.
Jax can't possibly afford to sign him. They are stuck with Bortles $19 million , even if they cut him due to his off season wrist surgery. He would have to agree it a contract with very little money up front, 10mill or so for the first 2 years with no guarantees for years 3-5. Taking less money is one thing, leaving $130 Million on the table is completely different.
The Jets are not a great team by any stretch but the D has good young pices, the Receivers are young with promise, the TEs have potential, and there will be $60-70 Million left to sign FAs and the 6th pick and 2 seconds can retool the roster in year 1. Year two will be similar with plenty of cap space and draft picks. Cousins is high on Bates, if familiar with and wants to play in his system. I think the Jets are in a good position going forward.