There are many good subjects for m com and some of them are as follows.

1) Organisation behaviour and management process

2) Managerial economics

3) Marketing management

4) Business environment and policy

5) Corporate governance

6) Financial management

7) Elements of income tax

8) Computer applications in commerce

9) E-commerce

10) Mergers and acquisitions

11) International trade theory and practice

12) Research methods and Statistical Techniques

For knowing the best subject for M, you can go through the link given below.

Link :- https://www.careers360.com/list-of-management-courses-in-india

I hope your question has been answered properly.

All the best for your future!