[jcal93]

One big thing RHEL has going for it is that it has a DISA STIG, which Ubuntu/Debian/other distros lack, so it's firmly cemented as the distro of choice for some DoD networks. Otherwise I think Ubuntu and its plethora of spinoffs seem to be taking the lead.

[warner25]

I thought there were STIG checklists for Ubuntu now, no? https://ubuntu.com/security/disa-stig

With that said, you're right that RHEL is firmly entrenched in the DoD. I previously worked in a DoD shop that ran a fleet of RHEL servers (still enjoying, and paying a lot of money for, Extended Life-cycle Support to RHEL 6...), and when I left that job I decided to start using Fedora on my personal laptop to stay in touch with Red Hat stuff, in case I ever wanted to go back to a job in that world.