For many Premier League fans, the answer is an obvious one, as the former Manchester United boss won a scarcely believable 13 titles out of 19 since 1993.
Arsenal fans too will be keen to point out the significance of Arsene Wenger's achievements, as the Frenchman did something that Ferguson never could - going a whole season unbeaten in the league.
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The question is further complicated when you factor in European conquests.
Pep Guardiola's many successes, which includes steering arguably the greatest club side of all-time to a pair of Champions League titles, has to to be factored in.
Jose Mourinho has also won the Champions League, arguably in even more impressive circumstances - guiding Porto and Inter Milan to European glory against the odds.
Each fan will have different criteria for measuring managerial success; from influence to legacy, to trophies won.
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To try and get a definitive answer, we at SPORTbible put the following question to fans on Twitter: All in their primes, their absolute peaks, which manager are you taking for your club?
Fans had a choice between Sir Alex, Wenger, Guardiola and Mourinho - with the poll soon yielding a clear winner...
Rather predictably, Sir Alex Ferguson received 67,7% of the votes, with the Scot's longevity, and astounding trophy haul simply too hard to ignore for many.
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Pep Guardiola was a distant second at just over 12%, with Mourinho on 10,9%, and Wenger last on 9.7%.
In the replies, a number of Twitter users explained exactly why Ferguson was the runaway winner.
"Fergie without a doubt. 13 league titles out of 19. That's coming from an arsenal fan who knows how much of a legend wenger is," one reply stated.
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Another user added, "If this is anything other than a Fergie landslide then football Twitter has officially taken over."
However, while the overall result was a clear win for the legendary United gaffer, Some were keen to suggest managers others who didn't make the four name shortlist.
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Whatever your opinion, the fact remains that English football has been thoroughly enriched in recent years by the addition of these legendary coaches, all of whom left a permanent imprint on the Premier League - and football as a whole.
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Topics: Jose Mourinho, Pep Guardiola, Sir Alex Ferguson, Arsene Wenger, Premier League