We were long time users of TravisCI, but switched to CircleCI because of the better user interface and pricing. Version 2.0 has had a couple of trips and hiccups; but overall we've been very happy with the continuous integration it provides. Continuous Integration is a must-have for building software, and CircleCI continues to surprise as they roll out ideas and features. It's leading the industry in terms of innovation and new ideas, and it's exciting to see what new things they keep rolling out.