Westcott Rapid Box Switch Octa-S Softbox (26")

I love this size. It's small and portable and I can use it as a basic diffusion on my strobe or it acts as a kind of beauty dish for portraits. I highly recommend paying the additional cost to have the Rapid Box version. It makes it as easy to open as an umbrella so you don't have to deal with getting the metal rods into the speed ring which can sometimes be a pain and rather finicky.