Used to use Mesos at my last job. It was ok, but the tool ecosystem around it just didn't stay up to date with the needs of the industry. Secrets, Ingress, Cron type problems were difficult to manage and we had to write some in-house stuff to handle it. The zookeeper backend was a pain in the ass of course. Upgrades and recovery from master failures sucked.

I'm not saying Kube is the easiest thing in the world, but in OSS DevOps what you need is an industry standard with a good tool ecosystem. And Kube has that.