DUG and SCO are highly correlated with the more liquid ERY, so they both get the boot.
DXD and FAZ are highly correlated with the more liquid SDS, so those two get the boot.
MZZ is completely illiquid and highly correlated with TZA, so it gets the boot.
EPV, FXP, SMN, SRS, TYP, YCS, and ZSL are all illiquid -- all get the boot.
Even though QID is highly correlated with SDS, I'll keep it for now.
VXX is very liquid but I prefer to keep the inverse XIV instead.
So that leaves us with: DZZ (gold), EDZ (emerging markets), ERY (energy), EUO (Euro), QID (Nasdaq 100), SDS (large caps), TBT (long treasury bond), TZA (small caps), and XIV (inverse VIX).