No one, we don't need a leader. We need decentralised governance.
That's not how it works though, is it? What you're really saying there is global governance.
Which faction that emerges as a dominant ever says "Oh no! We better stop using our advantage to improve our condition".
We have that. What has broken down is cooperation. The kind that has ensured relative peace for 80’ish years. That order is breaking down and creates instability. Instability means more conflict and less productive use of resources.