i would say ca's r best in their field but not all mba's r best in their field.A CA is a professional who is full of knowledge while a MBA may or may not be full of knowledge as it depends a lot from d institute from where u do mba.A CA work is very autonomous unless he is a great CA but the work of an mba is very challenging and needs a lot of effiency.The growth of a CA is steady and continous but it multiplies in case of a MBA and is faster also.......so better option is to do ca & then mba from a good institute otherwise its useless to do mba.