Exchange traded funds have become very liquid (you may sell and buy them very fast) which is another important advantage. Some of the most traded ETFs are: SPY (tracks the S&P 500 index), XLF (tracks the S&P Financials), QQQQ (tracks the Nasdaq 100 index), DIA (tracks the Dow index), IWM (tracks the Russell 2000 index), etc.
Naked options trading is very risky - many people lose money trading them. It is recommended contacting your broker or investment professional to find out about trading risk and margin requirements before getting involved into trading uncovered options.