Burnwinter
It's a tough question. You could make a case to improve upon pretty much every player in this team, aside from Saka, Saliba and Gabriel who I believe are as good as it gets.
A better shot stopper than Ramsdale.
A better attacker than White.
A stronger defender than Zinchenko.
A more reliable midfielder than Partey.
A more incisive midfielder than Xhaka.
A more creative midfielder than Odegaard.
A better finisher than Jesus.
A more creative winger than Martinelli.
We have a team which doesn't have an obvious weak link, so it's going to be difficult to improve it without upsetting its balance and chemistry.
I think adding more players at the teams level who give us more flexibility in options is where we can add value. Finding long-term replacements for Xhaka and Partey will define this teams potential, because those two hold this team together. We can't afford to make any mistakes in our midfield recruitment.