My feeling is most engineers prefer Debian. It's managers that tend to prefer corporate solutions.

As an engineer I don't care. In my career I have worked on SunOS, SLES, Debian, Ubuntu, RHEL, CentOS, Alpine and probably more.

I prefer something that is kept reasonably up to date so that I don't have to fight ancient long-fixed issues or missing features. But I really don't care, if it pays the bills I'll use it.

Going back about 15 years with this, but I used to prefer Debian / Ubuntu as a user, but for automating pxe installations and setting up package repos, Redhat/Centos were miles better.

So as a daily desktop user, how different are they in a professional environment?

Depends on what you mean. Advanced GUI is much better on SUSE though https://yast.opensuse.org/