An umbrella is like a shotgun - it spreads light everywhere, and it means EVERYWHERE! Just aim it in the general direction, and you're bound to hit something.
A softbox is much more directional, and easier to control. A softbox's light pretty much only goes where you aim it. If you need further control over light spillage, you can add a set of louvers to your softbox, which will really fine-tune the light fall-off.
Now I can't make my mind.
May I have your ideas here?
Thank you in advance.