Choosing a specialization depends on your interest & your graduation background, and your skills. There are many specialization in MBA & each has its own value in its field. but few of them which consider as top of the specialization in MBA  like Finance, Marketing, Human resources, Operations etc.

MBA Finance : MBA specializing in Finance focus on management accounting and control, the Indian capital and Money Market, Banking, and international Finance.

With MBA in Finance you can think your career in banks, financial consultancies and financial institutions.

MBA HR : It is all about recruiting, training, team building, performance updates, employee policy, salary, benefits and increments, employee health and safety as well as staff Amenities.

MBA Operations: Operations Management is the function of managing the operating core of an organisation: the activities associated with creation, production, distribution and delivery of the organisation's goods and services.

MBA in Sales & Marketing: An MBA in marketing will help you enhance your skills & knowledge in the field of marketing, advertising, public relations etc. It can lead you the packages as Brand Manager, Project Manager, Sales Manager, Marketing Manager, Market Research Analyst, Area/Regional Manager.

The choice should be your as per your capability.

Good Luck!