If you are in a dilemma what to use umbrella or soft box you are not alone. Every photographer goes with this phase.There are many different types of light modifiers reflectors and light modifier kit in the market.
The two most common are umbrellas and softboxes. So what you choose ? You first ask yourself which light you have or you want to buy ? because it all depends on the light you are going to use ! Standard softbox don't goes to speedlight or flash (unless you have this bracket).you have to have a special softbox bracket to mount the softbox on flash.
On the other side umbrella directly goes to either speedlight or studio light both.
These videos will give you a look at the umbrella versus softbox debate and information on the difference between the two, what they do, and which one to use. This first one by Phlearn shows a few options and talks about the relative size and distance to your subject as well
Next up is Michael from Smoking Strobes with a video from an outdoor workshop where he talks about the pros and cons of umbrellas versus softboxes when working on location outdoors.
Check our related article :-Using umbrella with flash light