It's a tough one this, but I'll go with:
----DDG
Valencia/Dalot - Bailly - Lindelöf - Shaw/Young
Fred- Matic - Pogba
Lingard
Lukaku - Sanchez
RB: Depends on how quickly Dalot adapts to the league.
LB: Depends on if Shaw can continue to improve and bomb forward like he did against Leicester
CDM: Matic provides extra defensive cover, but Pereira forward passing and greater mobility may mean that he's the better option against certain teams.
CAM: Mata may be a better creator, but Lingard is quicker and makes better runs. Again depends on the opposition imo.
CF: 2 up front with Lukaku and Sanchez, who I believe is better up front. When Sanchez plays on the left, both him and Pogba seem to take up similar positions. This should help to remedy that.
Formation: I went for a 4-3-1-2, to make better use of Sanchez/Martial/Rashford centrally. Also, factoring in that we don't have any RW's in the squad. This formation will require width and crossing ability from the full backs, so I have high hopes for Dalot on the right side as Valencia is somewhat limited on those fronts.