Qualifications in your chosen areas do give you a wide choice and so I understand why you are thinking about where to focus. First thing is to remember: where you start will not necessarily be where you end up. I started designing chemical plants and ended up as a CEO of a marketing and communications group, via teaching and computer games development.
MBA graduates usually end up in large organisations: multi-nationals, government and consultancies. I think I benefited from starting my career in a large organisation as there were many opportunities to learn.
So what is the "best fit"? It is difficult to say without knowing more about you. However, as a start, I think it is worth asking yourself why you chose Industrial Design in the first place. Is it still your passion? What kind of design problem interests you? Do some research and see which sectors and companies will allow you to fulfil your passion. If you cannot identify anything then I think focus on the MBA makes sense.
First, I think that it's great that you are interested in Industrial Design, as it is one of the fields where you can make an important impact and see the results. Having worked in a large company selling 3D Design software to industrial designers, I think there are at least a couple of opportunities. The combination gives you a solid foundation in industrial/manufacturing design as a practice, combined with understanding the operational and business context behind the design and manufacturing industry. You can take either a more entrepreneurial route by starting a design firm and using what you learned from your MBA to run and grow the business. Alternatively, you can work in product management or product marketing in a company that sells design software. For these types of roles, having background in Industrial Design is a big plus. In addition, you may want to consider getting an MBA with focus on Industrial Design.
It's great to hear you have degrees in both. Both John and Peter gave some good points to consider. I want to add one thing. There is an increasing trend for design schools to offer business programs and vice versa. Have you talked to anyone from IDEO in Boston? Have you checked out design thinking? Many companies are looking for people have design and business skills, even big consulting firm like McKinsey and BCG that are looking for people who have design and MBA. I have an industrial design background and worked in the design field for over 20 years. I don't design products any more. I am working on innovation, strategy, and enterprise transformation. What's constant? I am using my design skills and approach to solve problems.