Bayern Munich’s Neuer was nominated for the Ballon D’or award following his exploits for Germany at last summer’s World Cup.
Meanwhile, Ferguson brought De Gea to Manchester United in 2011 and the Spaniard has since developed into arguably the Premier League’s best stopper.
Ferguson believes the pair are as good in their position as Lionel Messi and Cristiano Ronaldo are as outfield players.
“Neuer and De Gea are the best goalkeepers in the world,” Ferguson said.
“And by quite some distance as well. You have Messi and Ronaldo as outfield players and then Neuer and De Gea as the goalkeepers’ equivalent.”
Ferguson had his eye on Neuer before he signed De Gea but the German opted to join Bayern from Schalke rather than make the move to England. De Gea struggled in his early months as a United player but the 24-year-old bulked up and now looks imperious whenever he is in-between the sticks.