Does Vanguard or State Street Have the Better S&P 500 ETF?

Vanguard's S&P 500 ETF (VOO) and State Street's SPDR S&P 500 ETF (SPY) are compared as two major S&P 500 tracking funds. While both offer nearly identical holdings and performance, VOO's significantly lower 0.03% expense ratio versus SPY's 0.09% makes it the better choice for long-term investors, potentially saving thousands over decades despite SPY's longer track record and slightly higher liquidity.