Di Stefano suffered a heart attack on Saturday and was in a coma before passing away on Monday afternoon.
Known as the 'Saeta Rubia' - the Blond Arrow - he helped Real Madrid win five successive European Cups between 1956-60 and scored in each of the finals.
He went on to coach Real, and former Manchester United boss Ferguson went head-to-head with him in the 1983 Cup Winners' Cup final when he was Aberdeen manager.
And Ferguson told Sky Sports News that Di Stefano, who played for Argentina, Colombia and Spain in his glittering career, should be considered one of the very best.
“The great question which always comes up is ‘who are the greatest players?’” he told Sky Sports News.
“There is a phalanx of great ones – Cruyff, Maradona, Pele, Puskas and Di Stefano. Di Stefano was one of the greatest in my mind.”
Ferguson revealed that he was one of the 127,000 fans in the stands when Real hammered the great German side of the 1950s, Eintracht Frankfurt, 7-3 in the 1960 final at Hampden Park.
“He had fantastic balance and poise – if you look at one of the goals he scored against Eintracht Frankfurt it was completely what we were talking about – the balance he had. Unbelievable, he was," he added.
“The amazing thing about that was that Eintracht Frankfurt beat Rangers in the semi-finals, 6-3 and 6-1. They came to Hampden Park as gods. They were then annihilated by Real Madrid in the final 7-3.
“I was in the schoolboy enclosure – I was playing with Queen’s Park at the time. It was the first time, I think – correct me if I’m wrong – that a lap of honour was done at the end. Scottish fans had never seen that before."
Asked if that was his standout memory of European Cup finals, Ferguson said: “In terms of European finals, it is. Ten goals in the final – you won’t see that again. It was a golden period for Real Madrid – five European Cups in a row with Di Stefano scoring in all five finals - quite an amazing record.
“But my greatest memory is Aberdeen beating Real Madrid in the Cup Winners’ Cup final in 1983. He was the coach at the time.
“It was an honour to come up against Di Stefano. What I did, out of respect for him, was I bought a bottle of Scottish Malt whisky and gave it to him the night before the match when the two teams had an opportunity to train on the pitch at the venue for the final.
“We were second, they were first. When he came off, they were coming down the tunnel and I said ‘Mr Di Stefano, I’d like to give you this gift.’ He was taken aback, he was really taken aback.
“He didn’t know what I was saying of course – I don’t speak Spanish, he doesn’t speak English. But there was an accord there – he was grateful.
“They were household names. But Aberdeen were a team on the rise, all brought up at Aberdeen, all Scottish lads. It was an amazing achievement. And after the game he was very, very generous.
“He said, ‘Aberdeen are a team that money can’t buy. They have a soul, and a family spirit'. Those words – you couldn’t say any more, in terms of praise for a football team. It was very generous of him.
“In the few times we played Real Madrid over the years he was always at the game, always at the reception. He was at the United celebrations for the Munich air disaster – he came along with the Real Madrid players. Of course they had played against Manchester United in the semi-final the year before. And they played them after the Munich air disaster in 1958.
“He was always the focus of Real Madrid wherever they went. He had a fantastic life and I’m proud to have been associated with him in a small way.”