As someone who runs a large build cluster at a major corp, Jenkins is clunky and outdated. It's a pain to deploy and keep maintained. I'd rather stub my toe than figure out why some event isn't being properly processed in the bowels of Jenkins.

However, when coupled with Kubernetes, Jenkins is more powerful than almost any other CI tool.

You can orchestrate any iteration of build types or actions while easily providing the underlying resources transparently to your users.

Notice that almost every other CI tool mentioned here is either 3rd party hosted or severely limited in some fashion when compared to Jenkins.