People hate and envy winners. SAF was not exactly revered by oppo fans as well.
There's a lot of similarities between Fergie and Mourinho in terms of personality - whether people want to admit it or not. It's likely why Fergie respected him as a manager. Both are winners, both would deflect attention to protect the team from criticism and most tellingly - neither are particularly bothered about their own popularity.
The recent spell at Chelsea sums up Mourinho's career to date - success, followed by a circus sideshow. That's obviously an issue he needs to deal with but ultimately he needs to settle down somewhere now and find stability.
He obviously doesn't come without risks, but over and above the other names mentioned on here he has a proven track record in numerous leagues of taking teams on and having success. The likes of Blanc and Allegri, whilst clearly very capable managers are in Leagues where the competition is mostly non-existent. Simeone has been impressive in Spain but being the underdog (and having someone above you making very good signings) is a different pressure to what he'd get here. The same can be said of Pochettino in terms of the position he's in now.
All in all, when it's weighed up, for me he represents the least "risky" option in terms of reversing the direction of travel and getting us back challenging at the top of the league and being a big enough name to identify and attract the type of player we need.
If that's for three years before a meltdown then so be it. He'd leave us in a better position that we are now.