Edit: And in the end, it's back to good old Fedora with Xfce. I guess I'm an old man, fixed in my ways. Haiku was interesting, but not nearly as stable as needed. OpenSuSE with Xfce was rough, it requires more polish.
I've been a Fedora Linux user for a million years by now, and I haven't touched any other OS (outside of Windows 10 and 11 at work).
Lately I got a refurbished ThinkCentre from ca 2018 (7th generation Intel i5, 16GB RAM, Intel HD 630). The initial idea was to use it as a media PC but the small form factor ended up not being small enough for my living room.
Now I'm thinking of using it as a desktop PC for a while, to see if it can make my laptop be a portable machine again instead of always plugged, always on. If it doesn't work out, I'll use it as a home server.
Since this is all an experiment, I want to give a new OS a shot before I settle for the familiar Fedora.
OpenSuSE is the first on my list, but even from the LiveUSB I noticed that the software selection is more limited than I'm used to.
I'm thinking of giving HaikuOS a shot as well.
What else has been going on in the world of free OSes since 2007? What's one that you are excited about?
Personally I am excited for immutable distributions, so my suggestion would be Fedora Silverblue or Kinoite. It may be a spin of Fedora, but it works completely differently than regular Fedora. I am using it as my daily driver for over a year already and I am quite happy with it (apart from reoccurring breakages caused by kernel updates, e. g. my AMD desktop currently does not work with kernel 6.4 or newer, but this doesn't have anything to do with Silverblue).
There are other immutable distributions out there, e. g. Vanilla OS or openSUSE microOS, so if you really want to avoid Fedora, you could also choose trying out one of these. In the case of Vanilla OS I would wait until version 2 is out, because version 2 will be radically different from the first release.
Silverblue is very "traditional" as far as immutable distros go. The main difference from regular Fedora I've noticed are the side effects of using rpm-ostree instead of dnf, which is that by using a base image, it is easier to track how an install deviates from the base image, and easy to swap out for another base set of packages by changing the image.