Cook or Warburton would seem like the sort who could bring attractive, entertaining football but unfortunately I think both have moved too recently and are doing well enough in those positions to not want to move on yet.
Rowett and JFH have both had great levels of success in the last 12 months but I've seen anything of either's sides to know how they play, reports I've seen of Blues seem to suggest they're organised and steady rather than a great watch, Burton romped League 2 last season but despite sitting 3rd this season only 2 teams in League 1 have scored less, which seems worrying.
Crawley and Swindon both played a nice brand of football against Wolves a couple years back from what I remember, could either of their managers step up? Dean Smith has always had Walsall playing good football, though their form has been very up and down until this season, could he do more with a bigger budget?