The thing about quality of competition is it goes both ways. Maradona didn't win four European Cups, but that was because he spent the prime of his career at Napoli, which would simply never happen today. He won a UEFA Cup back when that was a big deal, because only the league champion got into the European Cup and you often had the REAL best team in Europe playing in the UEFA Cup. They beat sides like Lokomotive Leipzig, who sound like a cupcake side to today's fan, but Loksche made the Cup Winners' Cup final the next year and only lost 1-0 to an Ajax side featuring Marco van Basten, Frank Rijkaard, Arnold Muhren, Aron Winter and a 17 year old named Dennis Bergkamp. So they weren't crap. Before the Bosman ruling, smaller clubs could be competitive in the transfer market and hold on to their players for longer than today.
However, Maradona dragged a bunch of bums to the 86 World Cup and 90 final is overegging it. Ruggeri, Olarticoechea, Burruchaga and Valdano were good players, they just don't have the eye-popping CV (except for Valdano, who played for Real Madrid) that today's players have. With only 3 foreigners - including other EU players - allowed in a team, a damn good second striker like Burruchaga was only getting to Nantes, instead of PSG or Juventus.
People are absolutely sleeping on di Stefano and Puskas though. Puskas and Cruijff are possibly the two most influential players in the history of the game, no two teams caused utter paradigm shifts in the game like the 50s Hungarians and 70s Dutch did. We are still, in almost every way, coming to grips with Total Football. Brazil's greatest tactical contribution doesn't involve Pele at all - it was a back four with attacking fullbacks (which is why Nilton Santos and Djalma Santos are criminally underrated).
Also, Michel Platini is deeply underrated now, due to him being a corrupt dick and the rise of Zidane. But Platini won three Ballon d'Ors and had the greatest tournament performance ever. Nine goals in five games for France's first major trophy win, Euro 84.