There are various options for you after 12th. You can go for the traditional commerce courses as well as other new courses. Some major fields available for a commerce stream students are- Traditional Commerce courses, Law Education, Management Courses, Educational courses. 

Some of the best & common courses are listed below- 

1. B.Com- This is a basic course. You can do specialization in any particular field after this. 

2. Law Courses- B.com+LLB, B.A+LLB, BBA+LLB

3. Management Courses- BBA, BMS, BBA+MBA, BHM

4. Technical Courses- BCA

5. B.A- This is also a very basic course. 

6. Mass communication

If you want to prepare for civil services there is not any particular best graduation course. It doesn't depend on your past stream. You need to be passionate about your goal.  

I would say you can go for economic honours or English honours. You have to choose some specific subjects for civil services exam and economics is among them. So if you do eco honours it would help you. Also you need to be really good at English to clear this exam. You need to write long articles (really long) . So doing English honours would help a lot too.

hope this is helpful to you