Why is upvoted so much. This just touches the surface. Although, I am not very related to PaaS, I know much more for the three of the methods listed. This even oversimplifies so many things, to the point of getting it wrong.

> WHEN TO CHOOSE DOKKU: for hobby and side projects that do not require high availability

Surely, not correct. Don't make your decision on this line. It's not made for fault tolerance, but anyone who has doubts regarding which to use is very likely to use a single region of single cloud provider. I think most companies(even large one) do that.

> Big caveat (for Kubernetes): it is very hard to setup

I really don't think he did that. It's really easy for AWS at least. See https://kubernetes.io/docs/getting-started-guides/aws/

> WHEN TO CHOOSE DOCKER SWARM: in my opinion, this has a very strong potential to be a contender against current solutions mentioned above but as of right now, it is still evolving.

AFAIK, it has been extensively tested and is being used live. I am not sure, but the amount of presence it has, it's hard to believe that it is just evolving and not to be used.