According to a survey of over 1,700 players conducted by the NFL Players Association (NFLPA), Detroit Lions defensive coordinator Aaron Glenn is the most popular coordinator in the NFL right now.
This survey was a new addition to the NFL report cards that gained a lot of traction when the NFLPA debuted them last offseason. This addition asked players to grade their own coordinators, with offensive players grading their offensive coordinator, defensive players grading their defensive coordinators, and special teams players grading their special teams coordinator.
So, in other words, no coordinator in football has the respect of his locker room more than Glenn, and that tracks based on everything we hear from his players.