I initially chose CircleCI for a personal project because I was not satisified with using Travis CI in the past. When it came time to develop my CI/CD config on Circle, I was pleasantly surprised with the fantastic documentation, invaluable collection of example configs and helpful support provided. The free tier they provide is quite robust for most small projects and the platform is updated frequently with nice features.
Areas where CircleCI could improve:
- the UI is a bit slow (you can feel the local machine straining to load all the code) and it is not as intuitive as it could be
- many UI elements receive updates and/or changes that are not always reflected in the current docs