ETFs w/ most active options trading:

$SPDR S&P 500 ETF (SPY.US)$ - 8.128M
$Invesco QQQ Trust (QQQ.US)$ - 2.948M
$iShares Russell 2000 ETF (IWM.US)$ - 1.095M
$Spdr Series Trust S&P Regional Bkg Etf (KRE.US)$ - 322k
$Ishares Iboxx $ High Yield Corporate Bond Etf (HYG.US)$ - 312k
$iShares MSCI EAFE ETF (EFA.US)$ - 249k
$iShares 20+ Year Treasury Bond ETF (TLT.US)$ - 221k
$iShares MSCI Emerging Markets ETF (EEM.US)$ - 214k
$ProShares UltraPro QQQ ETF (TQQQ.US)$ - 210k
$ProShares UltraPro Short QQQ ETF (SQQQ.US)$ - 188k
$iShares Silver Trust (SLV.US)$ - 148k
$iShares MSCI Brazil ETF (EWZ.US)$ - 145k
$iShares China Large-Cap ETF (FXI.US)$ - 143k
$ProShares Ultra VIX Short-Term Futures ETF (UVXY.US)$ - 136k
$Energy Select Sector SPDR Fund (XLE.US)$ - 135k
$Financial Select Sector SPDR Fund (XLF.US)$ - 128k
$VanEck Gold Miners Equity ETF (GDX.US)$ - 107k
$SPDR Gold ETF (GLD.US)$ - 104k
$Direxion Daily Semiconductor Bull 3x Shares ETF (SOXL.US)$ - 101k