The only Liverpool manager worth pitting against Fergie imo, is Joe Fagan.Here's my thinking,he joined just before Shankly and the period of their dominance.It was Joe who conjured up the "boot room" philosophy which is still the Lfc religion today.He achieved the treble like Fergie, something no other Liverpool manager has done,the UEFA cup treble doesn't count.He was both Shankly and Paisley's right hand man/coach as well as running the reserve team, bringing on some of the first teams future stars.He only managed for two successful seasons but how much of a factor was he in the previous success that Shankly and co take the credit for.
         Because of the treble and the culture he nurtured I reckon Joe was the best manager Liverpool have had,but still falls short of Fergies record/greatness. ;-)