Hello.
After 12th commerce there are various option to do, for selecting a best one you will have to see in yourself where your major interest is? If you have good accounting skills, analytical skills, integrity, and you are a risk taker, if you can do good hard work and time is valuable for you then definitely you should go for CA, while if your interest is towards computer science and you still have basic knowledge of your commerce stream then you can pursue BCA course.
Best of luck.