Di Maria racked up a total of 26 assists and 11 goals to help Real win the Champions League and Copa del Rey last season, before his eventual move to United in the summer.
Now, his United teammate has said he was more impressed with the Argentine than Ronaldo and Bale, despite the fact the pair scored a combined 73 goals in 91 appearances last season.
"Angel was a fantastic signing," Young said.
"Real Madrid have other top players in their team, like Gareth Bale and Cristiano Ronaldo, but he was the one who stood out for me in that team last season.”
The winger has also insisted that Argentine midfielder Di Maria has proved to be an excellent signing for United, despite his struggles to adapt in the Premier League and life in England.
Di Maria has only shown flashes of his ability for United this season, with excellent performances like the one in the loss to Leicester City earlier in the season often followed by indifferent displays.
Despite that, Young says that his quality can only help the side and he is definitely proving to be a great signing for the club.
"When you add quality to a squad that already has quality it can only help us,” he added.
"We saw in the first couple of days in training just how good a player Angel is and what we can expect from him. He was definitely a great signing for us."