Last night we fielded a team of Kepa, Azpi, Rudiger,AC,Alonso,Kante,Mount,Barkley,Willian, Pulisic and Giroud and beat City.
On Sunday we could field a team of Caballero, James, Zouma, Tomori, Emerson, Jorginho, Kovacic, RLC, Pedro, CHO and Tammy...with Gilmour and Batshuayi on bench and still have enough to beat Leicester City. There is a very good reason why both teams are where they deservedly are right now and its called squad depth. United can definitely field a stronger first 11 than us but on a 38 game season the level of disparity between your first eleven and the squad players who will have to fill in for them at certain points is way more crucial.
I look at United's first XI and their squad players there is a difference in quality whiles there is not much between our first XI and those that can fill in for them from the bench. If United can find a way to bridge this gap they can have a legitimate claim to have the best 3rd best squad next season but I don't see it.
We have already signed Ziyech to replace Willian and Werner to replace Pedro who has been a squad player for us this season.
With these in mind I think we have a credible claim as the 3rd best squad in the league and this might not change much even if United get Sancho for their first team and not improve the quality of their squad option.
You might opt to test your luck like Liverpool and hope your first XI stay fit throughout next season to carry you through but its a risk a team like United should be resourced enough to avoid.