jmc

The leading coefficient is the coefficient of the term with the highest power of $x$, which in this case is $x^4$. The coefficient of $x^4$ in $-3(x^4-x^3+x)+7(x^4+2)-4(2x^4+2x^2+1)$ is $-3+7-4\cdot 2=\boxed{-4}$.