If you had to choose a single light shaping tool, you might do well to pick the Impact 7' Parabolic Umbrella (White/Black) With Light Stand Kit from B&H Photo. In addition to the large 7' umbrella, this kit includes a 9.5' light stand, a triple-flash adapter mount, and an umbrella bracket with an adjustable shoe.
This 7' parabolic umbrella is a really huge, broad light source that wraps light around your subject, yielding clean highlights and rich open shadows. But due to the special shape of the umbrella there's a unique mix of soft enveloping light with the kind of crisp detail you only get from reflectors. Put another way, if you combined a beauty dish with a softbox, you'd have a parabolic umbrella.
This umbrella has a unique design structurally as well. The shaft is reinforced for strength and instead of bendable metal, the 16 inner ribs are made of durable fiberglass. The fixed black backing ensures that all of the light output is on your subject instead of through the umbrella. You can also vary the light-to-umbrella distance along the shaft for a harder or softer look or for longer throw capability. With the Impact 7' Parabolic Umbrella less is definitely more.
The Impact 9.5' light stand is heavy-duty black aluminum, with sure-twist section locks and air cushioning. Air cushioning gently lowers the light, preventing damage to light fixtures and fingers when section locks have not been properly tightened.
The Impact FA-300HS Triple-Flash Hot Shoe Adapter Mount allows you to mount, sync and fire up to three flashes from this single adapter. You can fire the flashes at full power for greater light output or, for faster recycle times, fire them at half power to conserve the energy. This unique adapter features a female 1/4"-20 thread for universal mounting, and may be combined with an umbrella, light panel, or other lighting accessories (all sold separately).
The Impact Umbrella Bracket with Adjustable Shoe is a versatile, lightweight metal bracket that includes a removable, reversible female stud to adapt to light stands with top studs smaller than the standard 5/8". An additional removable, reversible male stud mounts to the included flash shoe at the 1/4"-20 end, or to another accessory at the 3/8" end. The metal shoe features a knurled locking knob for secure mounting of all standard shoe-mount flashes.