Personally used nylon leaders up until relatively recently and don't think I'll go back in the lighter line classes; that is to say anything under 20lb.
Flouro is more abrasion resistant, lasts longer without weakening and personally I find it is less prone to breaking in the knot than the nylons I previously used. I used Maxima, YGK, Berkley trilene, Stren magnathin etc etc and the rockfish FC outperforms them all.
In anything over 15lb I use black magic leader material. Really rate it for everything from surface whiting (yes I use 20lb for yfw) to livebaiting kings,