Wenger is now the longest-serving boss in Arsenal's history and much of those 13 years at the Gunners have been spent going toe-to-toe with Fergie for the game's big honours.
While there have been plenty of confrontations, the pair have fostered a mutual respect in recent years.
Fergie said: "Arsene has brought the best out of Arsenal.
"Since he has gone there, the success of the club has been fantastic.
"He sticks to what he believes in — and so do his players.''
He added: "That is why he has been there so long. I read some quotes from his players the other day that sum up the situation pretty well.
"They owe everything to him. That is nice to read."
Ferguson, who has been United boss for 23 years, said: "If you look at Brian Clough, myself and Arsene, it proves longevity brings rewards.
"His team play the right way and he has a stadium that is full every week. He has been an incredible manager for that football club.
"There is no question about that."