At my previous employment, we used RHEL. Why? It is the only linux on the governments list of "security acceptable software products".

And lot's of CentOS. Mainly for development. If I needed a virtual machine to troubleshoot something, I would make a CentOS one. A lot easier to not worry about the license keys. Same for build machines and temp lab setup machines, CentOS was quick to set up.

Delivered machines required RHEL. The others did not.