Personally the reason I use a RHEL based distro on servers is due to third party tools that target RHEL, and also I am heavily invested in a personal knowledge base on the RHEL specifics such as how they implement SElinux, etc. Therefore I run Fedora on my personal workstations so that when a new release of RHEL comes out, I already know it.

But now I'm seeing more items target Ubuntu first. For example a colleague at work wanted me to get an overview of Swift -- for the longest time I couldn't get it for RHEL or Fedora, but could for Ubuntu. And a number of tutorial articles assume using Debian or Ubuntu. My main issue with Debian based distros is the package manager doesn't track enough metadata about packages (a lot is stored in a sequential log file that can get purged/rotated out, but isn't in a package database, such as install date/history/rollback information). That, and packages on RHEL / Fedora tend to install without needing input (they have sane defaults that you customize after), they also don't auto-enable when installing (so you have more control), etc.