I want to see young, hungry players designed to fit a particular system.
At the moment, Man Utd have no wide midfielders, and no wide attackers. Martial, Rashford, Lingard, they're not wide attackers. Sanchez doesn't count, he's gone. Fred, Pogba, Matic, Herrera, McTominay, Pereira, all are also central players. So there's no width except provided by the full-backs. Players also lack dynamism and aggression in midfield.
Therefore there need to be dynamic young players, who are still to make a name for themselves and for whom United are one of the ultimate clubs. Declan Rice is a good example of the kind of young player United should be looking to sign. Additionally, there need to be wide players brought in who actually ARE wide players. Jadon Sancho, Hudson-Odoi, are good examples of these. This will allow United to do what always used to be done well - make the pitch bigger, attack from a variety of angles, create space.
No player joining should see United as a stepping-stone, or a step down. That means no Barca/Madrid cast-offs, and a thorough review and interview process for players to check their character, which has simply not been happening.