Both CA and MBA have their own importance. There is nothing like this one is better than the other one. You can get good prospects with both the qualifications but what is more important is to be the best in whatever you decide to do. Yes, CA training starts right after class 10 and this is the time for you to enroll for it. In terms of money required to study the 2 courses, MBA definitely proves to be expensive than CA but time taken to qualify the CA exam can be more depending on your performance. Prioritize as to what is it that you are looking for in the long run.

All the best!
Counselor