For PaaS I thought the Heroku model was nice - the benefits of containerisation built into the stack and you don't have to manage any of it - ahead of Fargate and way ahead of K8s. On par with serverless, but with better compability with monolithic or partial microservice architectures, albeit higher cost.

There's no strong vendor lock-in either, buildpacks and backend services are much of a muchness across Dokku, Herokuish, Flynn, Cloud Foundry etc. If your app is 12-factor with externalised state, you're plain sailing with most PaaS and simple docker setups, or at least I don't get what K8s brings to the table in terms of operational simplicity.