Short answer, neither are better, just different.
Fuduntu generally does last longer in terms of support, but it's also using older software. Fedora has a shorter support period but is using newer software. Really it's tried and true software that's showing its age (Fuduntu), vs newer software that still has some bugs (Fedora). Fedora expects you to upgrade your OS sooner than Fuduntu, so this is also another facet to consider.
It depends on what you want really, if you just want a GNOME 2 desktop, then Fuduntu would be an excellent option. If you want a multiple choice desktop (GNOME 3, KDE, LXDE...) then Fedora wins out easily. You are pretty much stuck with the Fuduntu interface (though it is good), where as you have more options with Fedora (though it is not as finely tuned, it has a bit more of a bland, generic flavor to it.) In terms of interface it's a lack of options vs a less elegant design.
Both have the same level of stability. The last time I used Fedora it was stable except for the use of the Fluendo video player (crash) and Fuduntu with involuntary file lockout (such as a USB device, even with safe hardware detachment in use.) Though, these are only my experiences. You may have different results.
One last thing to consider, Fuduntu uses less system resources because of its older software, where as Fedora uses more because of its new software.
I hope this helps,