Security wise, I usually assume Fedora > Debian because of faster updates and generally more modern technologies.
Faster = latest features, less time for testing != more secure.
Stable = well tested.
There is a good reason why servers use stable distros (which also backport security fixes).
Idk to what extent that evaluation changes when talking about minimal variants running on Qubes. Where Kicksecure places in this ranking, I have no idea. On one hand, it obvioisly has lots of security hardening, on the other, it also has the biggest attack surface, so I could plausibly see it anywhere from “way less secure than debian-minimal” to “way more secure than fedora-minimal”
Such comparison has no meaning without answering “Secure against what?” and a clear methodology for evaluation. This is a huge topic.
I’m using seperate templates for every purpose/program, so I’m able to pick the best option for each specific use-case. The question is how do they differ, both in security and in functionality.
It depends what your goal is. Usually, it is a good idea to stick with stability for service qubes. If you want features, use a “faster” distro/repo for desktop stuff.