CF is a complete PaaS, isn't it? So it's not directly comparable to Docker nor Kubernetes.
From my perspective, CF seems far too large, monolithic (as in all-or-nothing) and opinionated, and honestly a bit heavy-handed and antiquated (the last two partly due to BOSH).
What's attractive about K8s in particular is the elegant, layered, modular, unopinionated design. K8s itself isn't simple, but it's quite small and lightweight, and its core principles are easy to understand; more importantly, it offers primitives without imposing a particular framework on anything (for example, it doesn't care about how the underlying host is configured or provisioned), which makes it a superb foundation for a higher-level PaaS, once someone designs that (maybe Deis).
We've already released a PaaS built ontop of Kubernetes at Red Hat, with the upstream named OpenShift Origin and the supported version named OpenShift Container Platform (https://www.openshift.com/container-platform/).
Our developers contribute a ton of work to the Kubernetes project, and pretty much everything that works on Kubernetes will also work on OpenShift. We do have some security settings by default that are more restrictive (like no containers running as root) but that can be easily modified to be more permissive.
From my perspective, CF seems far too large, monolithic (as in all-or-nothing) and opinionated, and honestly a bit heavy-handed and antiquated (the last two partly due to BOSH).
What's attractive about K8s in particular is the elegant, layered, modular, unopinionated design. K8s itself isn't simple, but it's quite small and lightweight, and its core principles are easy to understand; more importantly, it offers primitives without imposing a particular framework on anything (for example, it doesn't care about how the underlying host is configured or provisioned), which makes it a superb foundation for a higher-level PaaS, once someone designs that (maybe Deis).