I'm trying to remember my own experiences. For server uses I've used Ubuntu as that's what was used at work. For personal/desktop I'd generally use Xubuntu--next I'd likely try Kubuntu. I did try using Debian proper for a while but I ran into differences in how packages were built occasionally and considered the Ubuntu one correct because it matched expectations--generally vetted by more eyeballs using and writing about it.
Maybe switching to flatpak installed packages would eliminate the differences. It still feels like Debian is the distros' distro (like a musician's musician) and not for the masses.
This is great from a copyright and freedom point of view. But, if you're an end-user who just wants to get stuff done and have things work. Pure Debian gets in the way; that's not to say you can't work around it, but it is more work.
Ubuntu, Mint, Pop!_OS, etc. take Debian, add a layer of polish and make the system much more user-friendly.
I've always thought debian's main competition was ubuntu, which embraces non-free. Unfortunately it also actively scrabbles to keep a hold on your machine (try uninstalling ubuntu-advantage-tools)
Which is fine, I guess. Those who spend their evenings and weekends on software get to decide the goals and values of their project.
(I use a Debian offshoot.)
