Rooney and Ferguson did not always have the smoothest relationship at Old Trafford, although the striker became the world's most expensive teenager when the Scot signed him for United in 2004.
England captain Rooney won five Premier League titles under Ferguson, as well as the 2007-08 Champions League.
Ferguson retired in 2013 after winning his 13th Premier League title, with Van Gaal soon arriving as David Moyes' successor, the former Everton manager failing to complete a single season.
And although Van Gaal only had an FA Cup crown to show for his two years with a rebuilding United, Rooney surprisingly credits the Dutchman as the biggest influence on his career.
"Van Gaal is by far the best coach I have worked with - 100 per cent," DC United striker Rooney, who became England's record goalscorer, told De Telegraaf.
"His tactical skills, his way of preparing and his attention to the finest of details, I found amazing. I admired that in him. I had never looked at stuff like that before.
"Van Gaal knows that the way he works is tough for players. I made him aware of that at the time and we talked about this very well together.
"I regret how it all ended, yet I know one thing for sure - I have learnt a lot from him and I am definitely going to use those lessons for when I am a manager."
Ferguson was perhaps considered more of a man-manager than a hands-on coach, the Scot having delegated training sessions to assistants such as Steve McClaren and Carlos Quieroz during his latter years at Old Trafford.
Rooney, meanwhile, is thriving after ending a second spell at boyhood club Everton to join MLS side DC, but he is already planning to follow former international team-mates Frank Lampard and Steven Gerrard into management.
"It is great to see that Frank and Steve have been given these chances at big clubs," said Rooney, 33.
"That gives me hope too because I do think about these things. But for the time being, I am enjoying my life as footballer. I want to win more trophies.
"Physically, I feel good and I am still ambitious. But once my career is over, I am going to consider all the options."