The Blackburn boss admits to being left in awe at the ability of his Manchester United counterpart to continually churn out all-conquering sides.
Ferguson has overseen the construction of a global empire during his 23 years at Old Trafford, with his playing squad regularly re-moulded in the pursuit of success.
His ability to unearth hidden gems, nurture young talent and bring the best out of experienced professionals has seen United dominate English football since the inception of the Premier League back in 1992.
Ten titles have already been added to the Red Devils' trophy cabinet, along with two UEFA Champions League crowns and countless domestic cups, and Ferguson's men look well on course to add to that impressive haul this term.
"You can't see past them for the league right now and they showed last season they are the strongest side in Europe. They have got better since," gushed Allardyce in The Sun.
"No one wins the league and Champions League in successive seasons but they can. That alone will make them the greatest team Sir Alex has ever had."
UniqueAllardyce also believes that Ferguson will go down in history as one of the finest exponents of his trade, but admits the Scot appears to be showing no signs that he will be heading into retirement any time soon.
"He would miss it," added the Rovers chief.
"He thought through that period when he said it was his last year (in 2002) and then wondered 'What will I do after this?' Finally, he decided 'It is not time'.
"You'll never see another one like him. There is not a breed like him. That sort of man with that sort of dedication and total life commitment to football is something special."