If you are going to spend a lot of money on a winger then spend it on the most talented one, as long as you believe the motivation/commitment issues are fixable, which I think can be the case at a team like ours.
As for all the talk about output then I did list the output for a few wingers a while back. Cannot remember which thread it was in again though
Found it:
Last three years incl. this one, club stats only.
Rashford: 140 games, 49 goals and 27 assists.
Leao: 145 games, 43 goals and 42 assists.
Kvaratskhelia: 131 games, 36 goals and 35 assists.
Luis Diaz: 121 games, 35 goals and 18 assists.
Nico Williams: 124 games, 28 goals and 29 assists.