Stepney thinks it is a close race between Schmeichel and Van der Sar, but the former's all-round play made him the better goalkeeper.
"Obviously, it's between Schmeichel and Edwin for the title of United's best keeper," Stepney told the club's official website.
"I thought Edwin was fantastic in every way, he was completely different to Peter in so many respects.
"But Peter was awesome - his kicking, his throwing, his organisation and talking to his defence. He actually frightened forwards and not many goalkeepers do that today.
"I will say that when Schmeichel came to Old Trafford, he had to learn and he learned very quickly and, when he finished, he was the complete article.