Both the fields are great and have good career ahead. Now its dependent on your goal which will be the best for you. See if you wish to get a job oriented career just after your graduation, or if you have no wish to go for higher studies immediately in order to get a job, then going for the BTech in Biotechnology will be the best choice for you. The course will deal with a numerous number of problem in the Biomedical sector and you can discover a lot of impressive technique by studying the subject. Also the subject have good research opportunities as well. So if you are more of a job oriented person, and you want a job immediately after your Graduation then going for the BTech in Biotechnology will be a better choice. (If you wish to go for the BSc Biotechnology, then the jobs aren't that much in the sector. You have to complete the MSc in Biotechnology in order to get a good job).

If you are interested in research and you are interested to go for advanced studies in the Cancer Research, Virology, Molecular Biology etc then Microbiology will be the perfect course for you. See the job options just after the BSc isn't that much. So you have to do a MSc in the subject in order to have a job. But if you want to do great in the career such as you want to be a Medical Scientist or want to be a R&D scientist in different pharmaceutical companies then you need to complete your PhD compulsorily.

This are the important points most students are concerned of. You can consider the link provided below in  order to know more about Microbiology as a career-

https://www.careers360.com/courses/microbiology-course

For more information regarding BTech Biotechnology consider the link provided below:

https://www.careers360.com/courses/b-tech-in-biotechnology

I hope this helps. Wish you a great day!