CA

It is purely based on your interest and the area you wish to work in. The scope of work for a CA is mainly in the field of finance and accounting area whereas MBAs have more diversity to choose from.
There are CAs as well as MBAs who have climbed up the ladder and reached higher positions, though we may say that in certain areas like investment banking, financial consulting or mergers, and acquisitions, an MBA would be preferred than a CA.
On the other hand, there are instances of CAs who have picked new skills while on the job and handled greater responsibilities than someone who has an MBA degree.
There are also CA professionals who apply to international MBA programmes to have a shot at a global career.
So, we can sum up that a lot depends on the nature of your job, the related responsibilities and the learning involved.

If you are doing B.Com along with CA then it is a very good thing because you will be preparing for B.Com along with it. Also, B.Com is not a tough course and if you are going to take computers as a special subject then you are going to get more knowledge about computer and computerized accounting which is going to help you in both ways B.Com. Also while doing CA, if you take computer applications as a special subject, you will have chances to score more in comparison to other component subject. You have one more option which is taking up costing subject because all the portion of it is included under CA course and you will just have to study basics regarding this subject.
Moreover, if you want to score more in B.Com without studying more then the best way to is take these two subjects. So when you are going to pursue CA + B.Com, you will be passing from IPCC and going therefore for B.Com along with it will help you getting an add on degree with B.Com.