CS would be ideal if you are interested in establishing yourself in legal sector as it is more oriented towards corporate law. And CFA would be the best if you are considering a career in finance; like investment banking,stocks etc.
To read up more on CS log on to http://www.youngbuzz.com/careers/careerdetail/company_secretary
And for information on CFA log on to http://www.youngbuzz.com/careers/careerdetail/icwai-careers
This will help you with the career details like what is the career all about,scope,remuneration,career map and benefits.
Read through and kindly revert for further queries.