Here is why I think the Yanks have the better foundation "right now". They have the best hitter and pitcher of the two teams. Judge is better than anything the sox have. Cole is better than anything the sox have. Yanks also have the better pen. Looking at the rotation, Rodon and Cortes have a far bigger upside than any pitcher on the sox not named Bello. We also have proven big league starting depth in German and Schmidt. The question is, will anyone stay healthy? Yanks get a big edge on the mound.
On the offense, sox have the deeper team and I give the offensive edge to them. If Dominguez was healthy and knowing Volpe was going into year 2 plus Torres breaking out and Judge healthy, I would say it was close. But with Dominguez down for most of next year, there is no major upside beyond Volpe to think of beyond a last gasp return to prominence for a dying veteran.
In terms of the farm, you have top 100 prospects Wells, Pereira, Peraza, and Dominguez all MLB ready and having made their debuts. This injection of youth OR trade chips should help make this team more watchable. That being said, the difference isn't enormous. The sox have the more glaring issue. They've got a rotation that is shallow and talentless. If the sox add a few top level arms, they will surpass the Yanks