It all depends on where your interest lies. It's completely free choice as both have their own pros and cons, placement and opportunities and own uniqueness. Finance is always a preferred field for MBAs for its lucrative ROI, and growth prospects, more in financial ways than personal.

Operations on the other hand, is more of a backend opportunity, with limitless growth potential, more at personal, inter-personal and professional level.

https://www.careers360.com/courses/mba-in-finance

https://bschool.careers360.com/download/ebooks/quick-guide-to-mba-in-operations-management

Best wishes. Thank you.