As someone else has already mentioned, Drone is really nice.

We have a self hosted gitlab instance at work, so I use gitlab’s ci fairly heavily, and I really like it as well. And since hosting an entire gitlab instance just for ci is overkill (just use Drone in that case), you can just install the runner on your servers, and use Gitlab.com (you can make everything private). Which is a good option if you don’t want to setup & maintain something, as all it takes is adding the yum repo and yum -y install gitlab-runner.