Richard is exactly right - we cant' answer that as a question: particularly not in this case, because WCF and MVC are not comparable - they are completely different fields and do not overlap.
It will depend on the company and what it does: so talk to your supervisor and ask him. He may have a suggestion for a more appropriate subject! We can't give you a "do this" because we have no idea what would be useful in your current job, or company, or the company you may move to. They are both useful, and worth learning, but neither is "more beneficial" than the other without a heck of a lot of context.
You may get a better idea (or whole bunch of ideas) if you post the question here:
http://www.codeproject.com/Forums/1580229/General-Indian-Topics.aspx[
^] - at least the answers would be more targeted toward the country you are living and working in! :laugh: