All of the specialisations have equally good opportunities. It depends on the candidates knowledge to get that coveted job. It also depends on the institute in which you are pursuing your MBA. Hence I will suggest you to go to the specialisation you are interested in and success will follow.

A brief of various specialisations :

MBA finance:  It is a career field which requires one to possess skills in mathematics, economics, and financial theory, all of which are covered in great detail in a finance degree, specialization or track.

An MBA in finance balances mathematical rigor with management classes, and can be a good way to direct your career towards c-suite jobs in finance.

MBA Marketing: If you are interested in the entertainment, media, promotions, advertisement, sales and general management field, then the MBA is appropriate for you.
The marketing is the heart of any organization. The trend of marketing has changed and augmented with the technological evolution in the world.

MBA Operations: Operations management is chiefly concerned with planning, organizing and supervising in the contexts of production, manufacturing or the provision of services. As such, it is delivery-focused, ensuring that an organization successfully turns inputs to outputs in an efficient manner. The inputs themselves could represent anything from materials, equipment and technology to human resources such as staff or workers.

MBA Strategic Management : It offers a solid foundation in business strategy as it applies to competitive businesses, corporate diversification, and government institutions. Skill in adapting to evolving business environments and Changing laws.

MBA HR: Students in an MBA program with a focus in human resource management can take courses in business strategies and concepts as well as corporate headhunting, benefits analysis, compensation management, and business coaching. Coursework typically involves basic business concepts and human resource-specific topics.

MBA IT and Analytics: While an MBA has not been necessary in the past to become a successful IT manager, the skills engendered by the MBA are becoming more and more essential as IT becomes increasingly ingrained across industries and business functions.