CERN went with AlmaLinux along with many other big names.

I remember when CERN stopped supporting Scientific Linux, probably because CentOS was doing such a good job.

Currently I think Alma, all the companies (and Fermilab (which used to maintain another RHEL clone)) seem to have gone with Alma.

That said, in theory, it's irrelevant: bug-for-bug compatibility and all that.

That That said if I was going to install one on a laptop I'd choose Rocky because it feels vaguely less commercial and I appreciate that.

My company went with Rocky. We are almost finished migrating production hosts from CentOS.

This is like asking if Python or Ruby is the defacto language.

Alma have consistently released the new upstream versions faster than Rocky, so I have decided to go for them. Both distros are essentially just debranded copies of RHEL, so IMHO the choice needs to come down to which organization you have more faith it.

At the moment, there is no "defacto", as both provide significant value.

As others have said, Alma has been awesome and blazingly fast on releases, both Rocky and Alma are very fast on security/errata updates, and Rocky has been excellent on testing/QA (as our identification of a pretty major PPC bug demonstrates).

Rocky has always been 100% open with all development and community involvement with every part of the process and always reproducible by others. While this is does add a bit of latency in the build and release process, we believe always having a diverse community involved is well worth the tradeoff.

Where we can do better? ... Messaging! I've become a personal target since starting Rocky, so I tend to not engage directly anymore. Luckily, we do have a new community team lead, and she seriously ROCKS!

It is necessary for the community to always have alternatives. This is what will ensure that an open source Enterprise Linux alternative will exist for everyone.

It is amazing to be part of this and we would love to have you and others join us and check it out for yourself: https://chat.rockylinux.org.