What container orchestration systems similar to Kubernetes have you used or are familiar with?

Besides Kubernetes, there are other container orchestration systems I am familiar with or have used:

• Docker Swarm — built-in Docker orchestration system, easier to set up, suitable for small clusters.
• Apache Mesos with Marathon — a more scalable platform supporting not only containers but also other types of tasks.
• Nomad by HashiCorp — a lightweight and easy-to-use orchestrator, well integrated with other HashiCorp tools.

Each of these systems has its own features and is suitable for different tasks and project scales.