Temi, what do you want to do in the longterm?
If you want to do pure research, then a PhD would be a good idea. However, it's 3 years plus writing up if you go full time, or a lot lot longer if you want to work and do it part time. And it won't necessarily improve your career prospects either.
If you want to work your way up a company and be more senior management, an MBA is probably more what you want. However, I'm not sure how much research is involved as aprt of it. It's really more a management degree.