Fergie famously said at one point during his reign at Pittodrie there was only one job he would leave for, and that was Man Utd.
Not sure how much of that was tongue in cheek, but the facts are that he turned down Wolves, Rangers, Spurs and Arsenal before he made the move to Old Trafford so it would tend to suggest that there was something in it. One thing that Fergie always made a big thing of was his relationship with Dick Donald and Chris Anderson and realised that this was something he was unlikely to enjoy elsewhere in football.