Which S&P 500 ETF Is the Better Buy: iShares' IVV or State Street's SPY?

Investors are evaluating which S&P 500 ETF offers the best value between iShares IVV and State Street SPY. Simultaneously, a comparison is being made within the energy sector to determine the superior buy between Global X MLPX and the iShares Clean Energy Fund ICLN. These analyses focus on identifying the most effective investment vehicles for tracking the S&P 500 index and diversifying energy holdings through specific exchange traded funds available in the market.