Hi Aditi,
Just to begin with... It really does not depend so much, what function you are in (Unless you have extensive years of experience), for choosing a specialization.
What really matters is you knowing what kind of job Function you want to get into. And that getting into such function means very much living that and working in it for the rest of your career life.
Here's a little perspective of the different specializations and the skills/personalities that I've observed in my batchmates in MBA-
-- My friends who were in finance are great number crunchers. so in any discussion they would see numbers. returns, risks, profits, balances: life at a b-school for them was like metrics. So most of these people may not be the best in "sales" but the kind of insights they offer is brilliant.
-- The ones who did marketing were totally different. Extroverts, mix fast with people, great talkers, these people have an external focus of control,, which can be the market/ customer.
-- The ones in HR are primarily one who are people oriented. you must remember that scene in munnabhai where j.asthana says we are not here to make friends with patients. we are here to cure them. i think hr ppl are natural counselors,, have a big stomach to keep secrets and are patient
-- If you are from commerce background it will give you an edge in finance for sure. Your number skills, logical thinking, analytical abilities will help you. But fin never works in isolation. Its one stream that will constantly interact with all departments of a firm.
-- You can also couple a Major in Finance with a marketing/ it/ ops as minor field. Most of my friends who went for finance on campus had opted for marketing/ ops combo.
Thanks