Should we buy a Nifty index fund, and which ones?

Index funds are a good option to consider for investing. However given the current state of the index construction and the better performance of other large cap, multicap funds we recommend that the allocation cover 2–3 fund classes (i.e. not just index funds).

Index funds are often late in adding good performers (after they start performing) and often late in getting rid of poor performers, because they passively mirror the index.

You can explore various funds portfolios here and also check out various index fund choices here.