Do you like tech a lot? If so, go MIS. Anything w/ Information Systems = decent money in the current climate although that could change in the future. The only downside is that you have to find your niche and keep up with the technology and industry. For example, the tech you work with for MIS may not be relevant in 10 years when you decide to leave the military so it won't be exactly practical. However, if you want to stay in the tech industry I would still value an MIS degree over an MBA any day of the week. Which leads me to...
MBA, it seems like everyone has one nowadays and I don't think it will differentiate you from the pack unless you're in a field where it's valued. For example, I came across a resume the other day for a tech position and the guy had a recent MBA. I threw it in the garbage and we all had a good laugh about it. We want to hire someone who has a specialized MS and/or tons of experience to boot (it was a for a senior position). The MBA actually hurt him in this case because we wondered why he was applying for a tech position after getting his MBA. He would have been better off not listing it at all.
All in all, I think an MIS degree + grad cert or industry cert in [insert specialty here] would go a long way if you wanted to go the tech route. An MBA would only help you if you're applying for a managerial position like a Project Lead or Chief Engineer or Program Manager. But usually they go the technical background + PMP route. However, one of my good friends was a CS undergrad + MBA and he rose to program manager. You don't have a strong tech undergrad so that would hurt you a bit unless you go tech master's. If you have the skills and desire to be a good manager, then not having an MBA isn't going to stop you. However, getting MBA also doesn't mean you'll have the skills and desire to be a good manager either. The cream will rise to the top regardless of degree.