We have been using Travis CI for some Open Source projects, but recently started looking for a new CI platform for our custom projects for different clients.
The two solutions that seem reasonable are Jenkins and PHP CI, and since PHP CI is a PHP-driven project, it would fit better with our WordPress workflow.
However, we've been having a hard time making it work properly. Even though builds seem to be successful with a clean install, charts are not displayed due to fatal errors or warnings, and other conflicts have appeared due to the b8 framework. I cloned the latest b8 version manually, but it broke the CI server completely due to various dependencies.