MBBS is a better option if you're not clear on your specialization at the time of admission. It will offer you the chance to explore and research different fields before nailing down one particular specialization.
I would recommend BDS only if you're sure about dentistry from the very beginning. Many of my friends took up BDS because someone in their family was in the same line, and ended up regretting their choice. Going into a field like medicine requires a great amount of conviction. If you have even a speck of doubt whether BDS is really the right option, go for an MBA and keep your options open.