Neither.
M. Tech degree other than from the top 8 IITs, IISc and BITS doesn’t really count for much, except for govt. jobs or teaching jobs in the numerous private so-called engg. colleges which are available at every street corner in India.
So you will get a notional degree with little value and potential use other than that mentioned above.
The other thing is that Bio-tech while appearing as an advanced subject is really little known in the country with no standard definition. You are likely to get different answers on this depending on whom you ask. Hence employment prospects in pvt. sector are likely to be pretty limited. Govt. sector may be a better bet here.
If the intention is to do research, then this should be a good area esp. in research institutions in India as well as abroad. There is quite a bit of govt. funding in this area