For anyone who doubts Koeman is a good choice, compare his record at Southampton to Pochettino's. I think most on here would love Pochettino as manager, but in Koeman's two years at Southampton he's achieved a higher points total than Pochettino did there, despite that fact that several of their best players were sold in the past two summers.
With more money to spend and a better squad Pochettino has moved Spurs onto the next level. Maybe Koeman could do the same for us. Yes, he wasn't great at Valencia or AZ, but he was only given 5 months at Valencia and 3 months at AZ (but still better than Pochettino at Espanyol in both cases) and most managers have the odd blip on their CV. Just look at Mourinho at Chelsea this season.
For those of you saying he's only done at Southampton what Moyes did for us, it's now much harder to achieve a top 7 place than it was during Moyes time and we're talking about Southampton here, who were playing in League One not so long ago.
All four of the serious candidates mentioned have at least some element of risk attached to them.
Pellegrini's City are in grave danger of missing out on a CL place and, despite the vast resources at his disposal, still have a dodgy defence.
De Boer hasn't managed outside of Holland and Ajax finished a distant 17 points behind PSV last season in a weak league. What happened there?
Mourinho doesn't appear to cope very well if things go wrong. Until this season, he's always been at clubs challenging for titles, so when the wheels came off at Chelsea he looked like a rabbit caught in headlights because his massive ego couldn't comprehend what was happening. I kept expecting him to say, "But I'm the special one." I'm not sure how he'd cope if he did end up coming to Everton and got off to a bad start.
In an ideal world, it would be great to get Mourinho and it would be a massive statement of intent, but I think Koeman would still be a good appointment.