However for me I believe Ademola Lookman is more good than Nico Williams and will perform better than Nico Williams, we have seen how good Ademola Lookman is and if he is in a club like Barcelona he will perform very well and he will shock a lot of people his a very good player and I'm very sure he will work with Yamal very well.
Good luck to Barcelona I love the move they are making to adding another good player to the squad, I believe next season they will perform even more better.
Nico Williams is younger than Lookman and he has two big advantages against Lookman: his experience in La Liga is what Lookman does not have and will need time for adaptation to a new league; and his understanding as well as good combination with Lamine Yamal in Spanish national team recent years. It is another disadvantage of Lookkman who will have to get familiarized with Yamal and build up bonds with other new teammates.
I believe transfer prices of Nico Williams and Lookman are not too different and both are expensive. However perhaps Nico Williams will cost Barcelona more money for his wage.
In my opinion, it is best if Barcelona will neither buy Nico Williams nor Lookman in order to focus on improving their club finance and resolve current debt gradually season by season.