Any valuation applicable for an individual security will be applicable to the ETF as applied to all of the ETF's holdings and weighted by holding amount to arrive at an intrinsic value. But this is generally impractical and not what investors utilize ETFs for.
Given an ETF is an aggregation of individual securities, you can utilize traditional valuation methods on the individual securities (DCF, comps, precedents, etc) and weight them by the weight they have in the index to come to an 'intrinsic' value. Given that's a very cumbersome process, I think most investors will focus on finding undervalued individual securities for active investments.
ETFs generally function as a way to get exposure to an asset class, either for a long-term passive investment or actively hedging other parts of a portfolio. I'm not aware of any significant investment in ETFs as an undervalued security itself given there's more work with less upside potential than just going for individual securities. That being said, if you have definitely decided you want exposure to India, and now you are trying decide what asset class in India you'd prefer exposure to, there are several things to consider:
- Future/historical growth of each asset class
- Volatility of each ETF historically
- P/E ratio of each ETF
- Correlation of each ETF to the others (as well as to broad indices like the S&P500 and global equity ETFs)
After gathering that data, a picture will start to emerge and you can start to make judgment calls on what you think is the most attractive investment given the risk/return, current market valuation, and the dependence/independence of the asset class to others.