what are the best etf funds to invest in?
['SPDR S&P 500 ETF (SPY)', 'iShares Russell 1000 Growth ETF (IWF)', 'Vanguard Value ETF (VTV)', 'Schwab U.S. Dividend Equity ETF (SCHD)', 'iShares Edge MSCI Minimum Volatility USA ETF (USMV)', 'Vanguard FTSE Developed Markets ETF (VEA)', 'Vanguard FTSE Emerging Markets ETF (VWO)', 'iShares Core U.S. Aggregate Bond ETF (AGG)']