IBM Rational ClearCase might be better suited for a smaller / simpler code base. Larger code bases really slow it down... but then again there are better alternatives out there for source control
Mirantis is well suited for someone who doesn't mind spending money but doesn't quite want to commit to a cloud provider like AWS. It is also well suited for small or junior technical teams that don't have the skills, experience, or time to run their own openstack clusters.
Rational ClearCase is excellent for handling versioning and branching. No other tool I've used has the depth that ClearCase has when it comes to handling complex branching scenarios and identifying where certain versions of particular files are within a particular configuration.
Rational ClearCase handles parallel development of many dependent applications really well.
The use of ClearCase Views to switch between projects and configurations is extremely convenient as opposed to the local workstation model of the competitors.
Mirantis OpenStack managed services are expensive. Very expensive for a start-up.
I'd personally like to see a little more under the hood details in the status pages.
Mirantis could also benefit heavily from a free "light" version that start-ups could use to run their own cloud. Maybe coupled with advertising or some sort of surveys.
If development is centrallized to one location and your company releases hundreds of customized versions of your software per year, then ClearCase is the best tool for managing the complexity of multiple versions of customized software. If your company has globally distributed development, then I'd recommend Team Foundation Server over ClearCase. If your organization uses Agile Methodologies, then I'd recommend TFS with GIT.
Mirantis OpenStack for Kubernetes is easily manageable and has seamlessly configurable containers. It also has high reliability and security, which is certainly a positive point for this product. Overall I think it is a worthy competitor in the market to compare for your needs.
Mirantis did help our business figure out if openstack was right for us.
Using Mirantis I felt a bit cheated on understanding the deep technical knowledge of how openstack works. But that being said that is probably a value add more than a detractor for most people.
