Erik ten Hag has overachieved at Ajax.
Before ten Hag's arrival, Ajax hadn't advanced out of the Champions League group stages since 2005/06 season. And ten Hag achieved that in his first full season at the club. Getting out of the group stages was a problem for Ajax for over a decade. And he didn't just achieve that, he guided Ajax to the semi final stage for the first time since 1996.
He then started losing his best players to other clubs in subsequent years and has remarkably maintained a standard of play, which has seen Ajax still advance out of the group stages, when it was clear to see they were struggling to do that before his arrival for over a decade. When you consistently lose key players to other clubs it's very difficult to maintain a level of stability, but remarkably he's achieved that, whilst maintaining control both in and out of possession with lesser players in comparison to what we see in the EPL. Frank de Boer hadn't shown anything remotely close to ten Hag in the UCL.
And whatever one says about the Dutch league, one thing is clear from watching the league. And that is that the Eredivisie is closely contested. With the exception of last season when Ajax won the title by 16 points and PSV winning it by 17 points about 7/8 years ago, the league itself has been closely contested. Ajax won the league by only 3 points in the 18/19 season and on goal difference the following year. Teams like PSV and to a lesser extent Feyenoord and AZ in recent years are more than capable of winning against the so called lesser teams. The league is competive at the top. And then if you take in to account that Ajax have consistently lost their best players in the last 2/3 years, then that can only help PSV, because it's difficult to maintain a stability when you have to replace those top players that have been lost.
My personal preference was Luis Enrique due to his imposing style of play and experience at the top level. But after him, Erik ten Hag is a easy choice for me, because his ideas on the game are superior to the other candidates. Erik ten Hag is a coach that implements a zonal positional game via a vertical axis that not only has the potential to control the game with the ball, but also without the ball via the counter press.
And if you're a fan like me that wants to see your club potentially play a imposing game in the opponents half whilst promoting technical play, without compromising on work rate and intensity,then ten Hag is the easy choice. And ten Hag's ideas will help the likes of Hannibal, Isak Hansen, Mainoo etc because he wants to dominate possession with a purpose.