Service Fabric.

Now, I happen to think Kubernetes is better, but you asked. Service Fabric was available to the public in 2016 but has been used internally since 2011.

Why would that matter? If their kubernetes infrastructure is the most polished and production ready of the bunch, then I’d say they’re the leader.

> Why would that matter?

Because you lead nothing if all you do is reuse the tools developed by the actual leaders. That's what followers do, not leaders.