Not my point.
Nico brings more than just pace. He's a well rounded player and would benefit playing opposite of Yamal (and vice-versa) rather than his brother who is a fine but also quite limited player.
If it's between Nico and Leao I take Williams any day. Also because I think he would be much cheaper because of his clause. Don't see Milan selling Leao (with contract until 2028) for less than 80-90m and they will probably ask for similar wages so don't see much difference there.
But as
@Andresito said it shouldn't be just down to those two. There are other (cheaper) options, just need to find them.
Or get a veteran stop gap like above mentioned Son and sign Antonito and/or that South African kid and add them to Dani R. and Virgili and see how they'll develop over next year or two. You never know in football, 6 months ago also nobody predicted Casado will be undisputable starter now.
You don't always need to spend big to get quality players. In fact we are usually more successful with cheaper players than big money signings.