We use CircleCI because of the better value it provides in its plans. I'm sure we could have used Travis just as easily but we found CircleCI's pricing to be more reasonable. In the two years since we signed up, the service has improved. CircleCI is always innovating and iterating on their platform. We have been very satisfied.

As the maintainer of the Karate DSL open-source project - I found Travis CI very easy to integrate into the GitHub workflow and it has been steady sailing for more than 2 years now ! It works well for Java / Apache Maven projects and we were able to configure it to use the latest Oracle JDK as per our needs. Thanks to the Travis CI team for this service to the open-source community !

I use Google Cloud Build because it's my first foray into the CICD world(loving it so far), and I wanted to work with something GCP native to avoid giving permissions to other SaaS tools like CircleCI and Travis CI.

I really like it because it's free for the first 120 minutes, and it's one of the few CICD tools that enterprises are open to using since it's contained within GCP.

One of the unique things is that it has the Kaniko cache, which speeds up builds by creating intermediate layers within the docker image vs. pushing the full thing from the start. Helpful when you're installing just a few additional dependencies.

Feel free to checkout an example: Cloudbuild Example

I use Travis CI because of various reasons - 1. Cloud based system so no dedicated server required, and you do not need to administrate it. 2. Easy YAML configuration. 3. Supports Major Programming Languages. 4. Support of build matrix 6. Supports AWS, Azure, Docker, Heroku, Google Cloud, Github Pages, PyPi and lot more. 7. Slack Notifications.

You are probably looking at another hosted solution: Jenkins is a good tool but it way too work intensive to be used as just a backup solution.

I have good experience with Circle-CI, Codeship, Drone.io and Travis (as well as problematic experiences with all of them), but my go-to tool is Gitlab CI: simple, powerful and if you have problems with their limitations or pricing, you can always install runners somewhere and use Gitlab just for scheduling and management. Even if you don't host your git repository at Gitlab, you can have Gitlab pull changes automatically from wherever you repo lives.

If you are considering Jenkins I would recommend at least checking out Buildkite. The agents are self-hosted (like Jenkins) but the interface is hosted for you. It meshes up some of the things I like about hosted services (pipeline definitions in YAML, managed interface and authentication) with things I like about Jenkins (local customizable agent images, secrets only on own instances, custom agent level scripts, sizing instances to your needs).