Ferguson, who helped conduct the draw at the Dons' Pittodrie home, sent Derek McInnes' side to Firhill on the weekend of November 30-December 1.
"It won't be easy for Aberdeen down there," said the former Manchester United boss who won the trophy four times during his period in charge of the Scottish Premiership side.
"However, Aberdeen are the only side to have beaten them convincingly this season, 3-0 at Firhill and 4-0 last night at home.
"It will be a hard tie and along with the Hearts v Celtic game I think these are the best two in the fourth-round draw.
"That said, Rangers also face a tough trip to Falkirk but they have done really well this season and I think Ally (McCoist) has done a great job stabilising the club and improving it from last year.
"They are still undefeated this season and I think they will be going to Falkirk with a lot of confidence."
Of Celtic Park as a choice of venue for the final next May, Ferguson said: "I believe that is the right choice.
"It's great that Glasgow has the Commonwealth Games and to support that it was obvious that they had to surrender Hampden Park.
"Celtic Park holds 60,000 - even more than Hampden - so I don't think anyone can complain at that. Obviously the other clubs will be hoping that if they get to the final that Celtic won't be there.
"This is the oldest trophy in world football and in my time up here I always thought this was the best cup you could win.
"In fact, Aberdeen's record in the League Cup was not very good, we won it once, but the Scottish Cup was special.
"We really took off on the back of winning the Scottish Cup in 1982 and went on a great run of success after that so the competition has always been cherished by me."
Fourth round draw:
Falkirk v Rangers
Albion Rovers v Motherwell
Culter or Berwick v Dumbarton
Clyde v Stranraer or Auchinleck
Dundee United v Kilmarnock
Queen of the South v St Mirren
Stenhousemuir or Annan v Fraserburgh
Brechin City v Forfar Athletic
Alloa Athletic v Stirling Albion
Ross County v Hibernian
Dundee v Raith Rovers
St Johnstone v Livingston
Partick Thistle v Aberdeen
Hearts v Celtic
Ayr United v Dunfermline
Inverness v Morton
Ties to be played weekend of Nov 30-Dec 1