When comparing Travis vs Concourse CI, the Slant community recommends Travis for most people. In the question“What are the best continuous integration tools?” Travis is ranked 7th while Concourse CI is ranked 13th. The most important reason people chose Travis is:
Travis is free for all public repositories on Github.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Free for open source projects
Travis is free for all public repositories on Github.
Pro Easy to set up and configure
All that is needed to set up Travis is a configuration file (travis.yml) in the root of the repository where it will be installed and Travis takes care of the rest.
Pro Github integration
Travis registers every push to GitHub and automatically builds the branch by default.
Pro Supports most technological stacks
Supports the most widely used technological stacks (Node, Ruby, PHP, Python etc...) for free.
Pro OSX & Ubuntu support
Travis' VM are built on Ubuntu 12.04 64 bit Server Edition, with the exception of Objective-C builds, which are based on Mac OS X Mavericks.
Pro Multiple test environments for different runtime versions
Travis supports testing for different versions of the same runtime. All it takes is some lines in the travis.yml
file.
Pro Supports more than a dozen languages
Support for C, C++, Clojure, Erlang, Go, Groovy, Haskell, Java, JavaScript, Perl, PHP, Python, Ruby and Scala.
Pro Great community
Travis CI has a large and helpful community which is quite accepting to new users and provides a great number of tutorials.
Pro Private repositories and personal support w/ TravisPro
Starting at $129 you can use TravisPro, that adds the option of closed-source, private, repositories and personal support.
Pro Excellent website user experience
Pro Local iteration
Debugging on remote build agents is a nightmare (especially without isolated builds). Concourse CI can be run locally. When there are problems with the pipeline definition, it can be run and debugged locally. That means it takes less time to find and fix problems.
Pro Flexible
Resources are to Concourse as plugins are to Jenkins. In other words, resources allow Concourse CI to do just about any work necessary in a build. But resources follow a "service provider interface" that makes them easy to build in any language (not just JVM languages) and have a clearly defined computing model, built for composition. Resources don't clutter UI or tax performance.
Pro Scalable, reproducible deployment
BOSH is an open source tool for release engineering, deployment, lifecycle management, and monitoring of distributed systems. Since Concourse CI is built on top of BOSH, Concourse can scale across many servers or be run in the Cloud.
Pro Isolated builds
Build isolation keeps workers "clean". There's no configuration drift of agents. Or flaky interactions between build jobs.
Pro Usable
Visual pipeline view makes it clear what the automation does. Simple navigation to logs makes it easy to understand what happened in a build.
Pro Simple
Concourse defines three primitives that, together, can express arbitrary features and pipelines.
Cons
Con Only partial .NET support
.NET support is limited to .NET Core and Mono.
Con Only GitHub support
It does not support BitBucket. So it's not in list for companies using BitBucket private or public repositories.
Con Relatively expensive
Commercial plans for Travis are relatively expensive compared to other tools. They start at $129/month.
Con Non-free for private repos
Travis CI was first built to serve and help Open Source Projects, but now they also have added support for Closed Source which unfortunately is not free.

Con No Windows support
Travis can only run tests on Linux and OS X operating systems; running tests on Windows is not currently supported.
Con Limited infrastructure options
The downside of building on BOSH is that a full, scalable deployment of Concourse CI requires AWS, vSphere, or OpenStack. If you don't already have these, any one of them can be a big effort to set up, just to get a build server running. Might not be a good fit for smaller teams.
