3. Zinedine Zidane

Teams managed this decade - Real Madrid
The top clubs in Europe desire nothing more than to win the Champions League title. As the greatest and most elite club competition in the world, teams spend hundreds of millions and fire managers yearly to capture the European crown.
In the history of football, only three managers have been able to win the Champions League (or the European Cup) thrice. There's Carlo Ancelotti, who took 12 years between his first and third title. The legendary Bob Paisley, who achieved the feat in four years and held that record for over forty years. Enter Zinedine Zidane - one of the greatest players of all time, the former French international made the Champions League his playground as he did a 3peat with Real Madrid in the competition from 2016 to 2018. To give this some more context, not a single team had been able to retain the Champions League since it was rebranded in 1992; not only did Zidane retain it, he did one better and kept hold of it for three years.
Initially, assistant manager to Ancelotti, the ex Galactico took over the reins as the first-team manager after the former was fired midway through the 2015-16 season. In that season, Zidane won the Champions League. In his next season, he did the double as he won the La Liga alongside the CL. In 2017-18, Zidane created history by winning the CL yet again and cemented his status as one of the greatest managers in the history of this competition.
Detractors of Zidane make the case that he just inherited a great squad with the presence of a peak Cristiano Ronaldo and that he was "lucky" in achieving what he did. However you may call it, the fact remains that the manager coached his team to do the unthinkable, and his tactical mastery in big games was nothing short of managerial brilliance.
Winning one Champions League title after inheriting a team midway may be termed lucky - winning three in a row is nothing short of pure genius and determination. Despite Zidane's lack of longevity in this decade (because he came into the managerial game late), his accomplishments in Europe's greatest competition are enough to warrant him a top 3 finish.
Zidane is one of the best man-managers of this era, as the respect which his players have for him is immense. The World Cup winner is now back with the Los Blancos, and if he is to win the Champions League title again, he might just start entering the conversation for the greatest manager ever.