Hello Sir/Ma'am. Both are good UG degrees but everything depends on the subject you are choosing. For example you choose computer science as your subject then BCA deals with computer applications,computer programming languages. etc. According to me BCA is better than BSc because BCA has better scope than BSc in Computer Science. Don't compare BCA or BSC, both are better, but BTech is much better than BCA or BSC. BSC CS is a General Course and BCA is a Technical Course, so getting job from BCA is easy than BSC CS. After BSC CS, you can do MSC CS or MCA both. But after BCA you can only do MCA.

Hey,
BCA or Bachelors in Computer Applications is a three year undergraduate programme that helps you understand the Computer languages in depth. If you are fond of internet and web applications then this is for you. The demand for BCA graduates is always high owing to the rapid increase in the IT industry.
On the other hand,Bachelor of Science or B.Sc is a three year undergraduate programme that can be done in various streams like Physics,Chemistry or Biology and the list is endless. If you are fond of Scientific knowledge and want to learn about different facets of Science then this is for you. You may go for your Masters after graduation and work in the research sectors or you can go further in the field of academics.
Both these fields are equally good and everything depends upon your calling.
Hope this helps.
Good luck.