Best softboxes to use on handheld boom?

The square Rotalux boxes are much quicker to set up than the Rotalux Octas, not just because half the rods but they are also less stiff because they only have to sustain a square or rectangle. Also take the deflectors for more versatility (square beauty dish, anyone?).

I would not leave a light outdoors on a stand without a person holding it unless there was no risk of wind, no risk of a person (or animal) walking into it and sandbags at the base of, preferably, at least a c-stand.