The best replacement for softbox is umbrella.

The best alternatives to softbox are rated as following:
★★★★★  umbrella
★★★  octabox
★★★  diffuser
★★★  beauty dish
★  umbrella lighting
★  no softbox
★  lightsphere
★  plm
★  shoot through umbrella
★  strobe
★  reflector
★  octobox
★  gary fong
  brolly box
  kino flo
  speedlight
  led panel
  umbrella light
  softbox
  umbrella product photography
  umbrella photo lighting
  bounce umbrella
  umbrella lights
  umbrellas
  shoot through

Your alternative for softbox is not listed? Suggest!
Speaking about softbox, one probably shouldn't forget about speedlight.

Other search terms related to softbox and their ratings are:
★★★★★ speedlight
★★ continuous lighting
★★ strobe
★★ speedlite
★ sb800
★ 580ex
light stand
You have in mind a companion for softbox and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of softbox in all years. Click on graph for more.
softbox
umbrella
octabox