While there are a lot of names floating around, I think the Titans decision will come down to three names: Dan Quinn, Mike Zimmer and Ken Whisenhunt.
While there are some similarities in these candidates, each has their own distinct specialty that makes them desirable to the Titans.
Specialty: Passing game
When Whisenhunt had his most success in Arizona he was using Kurt Warner and Larry Fitzgerald to torch defenses through the air. While he hasn't had that stud #1 WR that he did in AZ, Whisenhunt managed to make an aging Philip Rivers and a group of second-tier WRs the fourth-best passing offense in the NFL.
With weapons like Kendall Wright, Justin Hunter, Nate Washington, and Delanie Walker a head coach like Whisenhunt may be able to restore Jake Locker to his early 2013 form.
Specialty: Linebackers and interior DL.
ZImmer's brand of motivation seems to be particularly effective with the interior "triangle" of the defense. Zimmer turned an UDFA (Burfict) and a fourth round pick (Atkins) into two of the Cincinnati Bengals best players. If Zimmer can come in and find a way to turn the Titans defense into a top-10 unit, then teams like Indianapolis and Houston would have a much tougher path to an AFCS title.
Everywhere Quinn goes there seems to be an outstanding defensive line, and with a roster that includes Jurrell Casey and Derrick Morgan it is hard to imagine him not doing the same at Tennessee. With Quinn at the helm, and a good offensive coordinator like Mike Mularkey the Titans could be a huge rebound team in 2013.