The choice between an MBA and Masters in Engineering depends on personal interest. If you have a very strong interest in Engineering, then the choice is obvious and it is not the MBA. If however you are open equally to either of the two programs, then the MBA may be the right choice. The MBA would teach you the fundamentals of business in a systematic and structured format, thus making you more knowledgeable about the business environment, on top of the engineering knowledge that you have already acquired.

With a Masters degree in Engineering, you are most likely to work on engineering issues in your employment, at least in the foreseeable future. This means you will be spending your time with mathematics, technical challenges, and focused projects and tasks. With an MBA, you are most likely to work on business issues. This means you will spend your time dealing with money, people, and "big picture" decisions for an entire organization. Now please keep in mind that these descriptions of how you would spend your time are over-simplified. However, if one of the two paths looks much more interesting to you, the decision could be easy.

Two final important points: First, the decision should support your current vision of how you would be most happy spending your time each workday. Second, this decision does not have to limit you to one academic option and one career path. Because you are likely to have a long career, you will always have more options. You could get both degrees! And you are always likely to have the option to switch disciplines at work, regardless of the degrees listed on your resume. Good luck!