ETFs w/ most active options trading:

$SPDR S&P 500 ETF (SPY.US)$ - 7.171M
$Invesco QQQ Trust (QQQ.US)$ - 2.878M
$iShares Russell 2000 ETF (IWM.US)$ - 859k
$Ishares Iboxx $ High Yield Corporate Bond Etf (HYG.US)$ - 557k
$iShares MSCI Emerging Markets ETF (EEM.US)$ - 324k
$iShares MSCI Brazil ETF (EWZ.US)$ - 284k
$Spdr Series Trust S&P Regional Bkg Etf (KRE.US)$ - 277k
$ProShares UltraPro QQQ ETF (TQQQ.US)$ - 261k
$ProShares UltraPro Short QQQ ETF (SQQQ.US)$ - 208k
$iShares China Large-Cap ETF (FXI.US)$ - 203k
$ProShares Ultra VIX Short-Term Futures ETF (UVXY.US)$ - 199k
$iShares Silver Trust (SLV.US)$ - 180k
$iShares 20+ Year Treasury Bond ETF (TLT.US)$ - 176k
$Financial Select Sector SPDR Fund (XLF.US)$ - 143k
$SPDR Gold ETF (GLD.US)$ - 136k
$Direxion Daily Semiconductor Bull 3x Shares ETF (SOXL.US)$ - 129k
$United States Oil Fund LP (USO.US)$ - 102k
$Energy Select Sector SPDR Fund (XLE.US)$ - 73k
$Direxion Daily S&P Biotech Bull 3x Shares ETF (LABU.US)$ - 73k