It all depend upon what you are looking for in the future.  If you just want a graduation degree so that you can appear for UPSC examination,  I would suggest that you for B.Sc as it's a three year course and is not that tough. But if you are looking for career opportunities and good job scope, I would suggest that you go for BE CSE. Being an engineering degree it provide you placement right of the end of the college.  Also you can appear for UPSC after that too. So accordingly for me BE CSE is the best option for the best . Dont put all your eggs in one basket. Go for engineering and in case you dont crack the UPSC, atleast you would be able to get a job somewhere else