Both Karunya and Satyabhama are Christian minority institutions and it depends mostly on what you are looking for. You must know that Karunya University is strictly religious and they might force you to follow the same. Academics is their secondary focus.
Whereas, Sathyabama is a bit more lenient in this way. It offers great exposure due to its location in Chennai. It will be a better option for you when compared to Karunya. However, the facilities offered are not good and not even functional. The faculty members are also average and are not exceptional. It is currently a Deemed-to-be university
Both these institutes are subpar and if you really want to have a bright future, look for better options.