21. Marcelo Gallardo
South American teams are notoriously volatile to coach, so the fact that Marcelo Gallardo has managed to last five years in Argentina is a testament to his quality. The manager of River Plate, Gallardo has brought phenomenal success to his side of the past half-decade, winning trophy after trophy and playing entertaining football.
He’s won 3 Copa Libertadores, 1 Copa Sudamericana, as well as several domestic titles, making him the single most successful manager in the history of this prestigious club. The fact that he’s done so well on the continental stage has caused many fans and analysts to claim that he’s the greatest coach ever to manage River.