I only counted two that prefered a 5" fixed blade. I like the 5-5.5" (yeah, I know that's a "range"). I've found it the biggest fixed blade I can carry on the belt comfortably, conceals adequately under my ACU shirt or civilian jacket and can perform most tasks minus the heavy duty chopping.
For a folder, anything in the 4" range will do, and if I'm out bushwacking, I like a good 9.5-10" blade in addition to my fixed belt knife.
I have plenty of 4" fixed blades that are great for lower profile, hunting/fishing or typical camp chores, but that extra 1 to 1.5 inches on a 5-5.5" fixed blade makes a big difference for doing bigger knife chores.
ROCK6