India

Hi Uday,
I suppose you are asking this question from the context of an under graduation Student and reference to MS is to post graduation programme from (top)Technical Universities abroad and MBA from (top) B-Schools in India.
When it comes to choosing between an MS or MBA, you are effectively tossing up between a technical or managerial career for yourself. Although, it is a tough decision to make, the following pointers should help you. Mind you, both technical and managerial careers can be equally lucrative and exciting. Eventually that's what this is all about right, finding a good career prospect that's going to give you enough money and fame.
How much do you love Technology? If it is a 7 or more on a scale of 10, which can be gauged by simple things like, did you enjoy atleast half of your core engineering subjects, or did you get excited preparing for a lab/practical session, or did you participate genuinely in technical symposiums/contests etc., you are the technical guy and should go for a good MS programme in your field of study.
How desperately do you want to settle down in a very developed country like the USA? If you responded with a 7 or more on a scale of 10, then there are no two ways about choosing an MS programme, although you will need to take stock of your financial background as well before taking this decision.
If you answered in the 05 range for the above two questions, then you are better off doing an MBA, and of course based on your existing skill level and ability to dedicate time and effort you can set your sight on the level of B-School.