rkt is really a fundamentally different architecture and approach than Docker, but more importantly a large unmaintained code base. k3c is really a fairly light layer on top of CRI, containerd and buildkit. So the maintenance burden is very low and quality should be high given it's using the same technology as production Kubernetes clusters.

rkt's files read like it was designed by someone who was used to existing DevOps tools. Docker's format looks more like what someone would come up with from first principles. I don't think the rkt guys accepted that this was part of Docker's success.

rkt feels actively hostile and I won't be using it. If I work for someone who is, I can find a different part of the stack to inhabit until they change their minds.