We need two quality midfielders in the summer, that's by far the most important position to improve upon. The midfield is the brain of the team, they control the tempo and pace of the games. Partey is injury prone and has off pitch issues that is still in limbo, Xhaka is limited physically and technically, we have enough forwards to compete, especially when ESR gets fit and Balogun comes back next season.Indeed, Ødegaard is slow, one footed and was shut out today as well, yet he's been one of our best players all season you don't get this constant yearning for more dynamism.
Other than age, I don't see what makes Xhaka a priority to be upgraded other than the people who have always angled for it waiting for a loss. For me you'd be looking at one of the forward positions and spending the bulk of your budget there first and foremost.