Since all the index funds following the same index will reflect a similar investment portfolio, the decision to invest in a specific index fund must be based on two primary features, Total Expense Ratio (TER) and AUM (Assets Under Management). Since the absolute returns generated by all the similar index funds would be the same (subject to tracking error), the net returns would be dependent on the scheme expenses. The lower the TER, the better the returns for the investors. Additionally, a significant asset book for the scheme significantly helps lower the tracking error since the impact cost of making the changes in the investment portfolio as a percentage of AUM decreases. The higher the AUM, the lower the likely tracking error. One should choose the Nifty index fund with a lower expense ratio and higher AUM for a better investment experience.