Gunna jump in on this. SAF got some stupid talent out of the academy so in terms of turning them into stars - big tick. Not really something Klopp has probably shown in the short term. TAA, Curtis and maybe Elliott don't really compare at this stage.
Klopp on the other hand has taken a system that he developed and brought in above average players and turned them into superstars. SAF played a system to his talent. And he also had the advantage of stupid $$$'s for wages to keep these players at ManU. So from a club financial perspective, Klopp every day.
The big one though is longevity for the club. Hard to say as SAF was around so long, so knowing what he built survives afterwards is moot. Klopp leaves and we may struggle.
TBH, I have a condition where I see a ManU jersey on the ground, I have to put a turd on it so maybe I'm biased a bit. Will say that both SAF and Klopp school Pep every day of the week imv.