The Spain international has endured a tough time of late in English football.
Uncharacteristic errors have crept into his game, leading to questions being asked of his contribution and mindset.
A dip in his usually high standards has occurred amid uncertainty surrounding his future at Old Trafford.
De Gea is yet to commit to an extended stay with United past the end of his current contract, which is due to expire in the summer of 2020.
A move is now being mooted for the 28-year-old, with Paris Saint-Germain considered to be one potential landing spot.
Hoek, who worked alongside Louis van Gaal during a fellow Dutchman’s time with the Red Devils, believes that De Gea is deserving of a role at a leading club.
He claims the Spaniard would not look out of place at any side in world football, with his performances over recent years cementing a standing towards the top of the global game.
“I worked with him for two years at Manchester United and I must say he's at a really high level,” Hoek told Marca.
“It's not easy to play three games a week as is demanded in England and maintain a high level.
“Particularly when anyone can beat anyone there. But he does it.
“That's why it's unusual to see him make mistakes at international level. De Gea could play for Barcelona or City because playing with his feet is among his many qualities.”
Neither Barca nor City are in the market for goalkeeping additions at present.
The reigning Premier League champions have Ederson on their books, with the Brazilian considered to be the perfect fit for Pep Guardiola’s ball-playing philosophy at the Etihad Stadium.
Meanwhile, Marc-Andre ter Stegen is the undisputed No. 1 at Camp Nou.
Hoek also spent time working in Catalunya when Van Gaal was at the Barcelona helm and admits a Germany international on the Blaugrana’s books is another to fit into the world-class category.
He added on Ter Stegen: “For me, he is one of the best because at Barca it is very important to play well with the feet, but he is also fantastic at shot-stopping, in the one against one situation.
“He is a very modern goalkeeper, of this time and that has a lot of value.”