4) Romelu Lukaku (Everton)
Finally, in a slightly more ambitious move, United should try again to sign Everton striker Romelu Lukaku. The Belgian is in superb form this term and would be a huge upgrade on the off-form Wayne Rooney, whilst also taking the pressure off youngster Anthony Martial. Although he’d be expensive, Lukaku would surely cost less than pie-in-the-sky targets like Thomas Muller and Neymar.