I can't comment on India in BNW to any great extent, but I can sure add this to my earlier comments in this thread (which were about how managing arbitrary happiness numbers isn't an interesting UA).
It does little good in my mind for people to defend India's UB. It is certifiably terrible in G&K unless you get Neuschwanstein (and only then it's good because you'd have already built most of the castles before you finish the wonder as opposed to shortly after like all other civs who build it). To get the +2 culture (in the
LATE MEDIEVAL era, mind you), you have to first build walls and then castles in a lot of cities that otherwise do not need the defenses.
Compared to the Songhai who get +2 culture from temples which are then subsequently maintenance free, and are an otherwise useful building that comes in the classical era, the Mughal fort is terrible. Songhai's UB gives them way more flavor towards being a religious civ, and as a result they can just build a happiness oriented religion and outperform India in my opinion. The Mud Pyramid is on the same tech as the NC and their UA is much more domination oriented as a plus.
Edit: A few more things when it comes to warmongering in this India vs Songhai comparison..
The Mughal Fort and the walls that are required to build it can provide +1 happiness each thanks to honor policies. Songhai can do the exact same thing with walls and a castle. And the Honor opener is WAY better for Songhai.
The Mughal Fort requires walls which may or may not be useful for the given city. The Mud Pyramid Mosque requires a shrine which is always useful and both faith buildings can have their production time sliced with the Piety opener (and can have other benefits thanks to religion).
As someone mentioned, India has to expand more slowly meaning fewer faith buildings for "hard founding" a religion. Songhai has no such limitation.
Someone said that the elephant archer is more intended as a defensive unit while your population is increasing. I agree. The Mandy Cav while not great is certainly geared for city capture.
For warmongering, by taking Autocracy both India and Songhai can quick build courthouses. India's city if high pop will not be as happiness costly. Songhai gets triple gold for capturing cities and can purchase a happiness building or another unit immediately to continue steamrolling. Unless there is some other India Domination victory strategy I'm not aware of in G&K - win to Songhai.
About the only place where India tries to be on top is with the Mughal Fort's late gold bonus (soon to be tourism I guess). You can't guarantee being able to stack that with Neuschwanstein like you can guarantee stacking Honor and Piety Policies with Songhai. Also Songhai's temples are FREE. So in that category, even potentially post BNW I still say Songhai is better in the numbers. Murder by numbers for Songhai - and from earlier in the game when it's easier to conquer civs. You get about 20 - 30 more turns of culture out of your UB's than India. And I have barely even mentioned the other parts of Songhai's UA and their implications. And lastly, Piety and Rationalism can both be open now in BNW so that's another buff for Songhai! I pray they don't take away that +2 culture for balance... *out of breath*
For me it's not that India is bad - it's just not as good as people are making out! It's not pro, it's just
mild and boring!