I like to live on the edge of time and therefore have the feeling that debian based distros (although being very stable) are too “old” for my liking.
Nowadays, with Flatpaks, so many software providing binaries, etc. this does not matter so much. If you want, you can even use something like Distrobox to have containers for tools using whatever bleeding edge distro you want, but still have a solid stable underpinning.
Debian also has more stuff than you would expect in backports. The main sticking point is yes, you'll be stuck in Debian 12's KDE until 13 comes out. But that might be sufficient for you?
(You could also use Debian Testing, which is basically a rolling release. But I'd consider stable first.)
You need two drives for the OS, four for data. Hetzner boxes are cheap with 2 drives, cost multiplies if you add any other.