Despite the January addition of Bruno Fernandes, United are expected to be in the market for a new playmaker later in 2020, resulting in frequent speculation regarding bids for Maddison and Aston Villa's Jack Grealish.
While several reports have hinted that Grealish is more likely to move to Old Trafford, Stam feels that Maddison would have more of an impact at the North-West giants.
Speaking to 888sport: "I like Maddison a lot. He's a midfield player who is very comfortable on the ball and he's always going into certain positions where he becomes an extra man. He can go by players and score goals as well as creating opportunities for others.
"Jack Grealish, I see more as a winger coming in. For United, they need to look more at direct wingers with pace going forward, instead of a player like Grealish.
"Who knows, he might be an important player because he is good in tight areas. But for me, it's Maddison for United."
Leicester are said to be trying to agree a new contract with Maddison, who would cost United in excess of £60m.