Fedora is kinda the upstream testing distro of RHEL.
If you love RHEL or it's derivatives, you'll love fedora. Use it if you need the latest softwares and tools and still want to experience the same environment.
I recommend CentOS/RHEL for production though. It's a lot more stabler than fedora.
As for the talk of ubuntu and debian, ubuntu is a derivative of debian. But imho debian is better.
Bleeding edge distros are more suited for workstation environments (desktop, work, etc. )