I've switched my personal projects, and my employer has switched to Circle over the past year. Circle's dockerized strategy for building up your CI/CD platform means that they support the new version of X nearly the day it comes out. Historically Travis has been very slow at this. Their support for Postgres 10 was an embarrassment (https://github.com/travis-ci/travis-ci/issues/8537). It's also vastly easier to parallelize your test suite. With Travis we had to install a third party gem to run our Rails' across many nodes. We also had to hand-manage balancing. With Circle we simply followed the docs, and we're off to the races.