@manu, consider buying new devices. S7 is two generation old device now. It will not receive many software updates in future. It is also not very smooth after Nougat update, i use it as my backup phone along with my daily driver S8.
It was a good phone till Marshmallow version. If you can manage to stay with old version then it is a beast surely. Rest you decide.
If any questions, feel free to ask and i will be glad to answer.