There is! It isn't one of the big two, but there is a party that is anti-drone, anti-NSA, anti-drug war, etc.: The Libertarian Party[0].
That said: the current Libertarian Party has a lot of baggage regarding the religion of markets. While I think the market is a powerful and worthwhile engine of growth, I don't believe it is the only valid or effectual form of social contract. (I've come to adopt the term "Chomsky Libertarian". [1])
(I say this as a registered Green(-Rainbow). I'll be voting for Hillary unless it looks like she has a wide margin.)
Math-wise, the optimal strategy depends on the size of the effect that pull is likely to have, weighed against the odds your vote will change which of the frontrunners wins times the difference between the frontrunners.
Of course, ideally we could switch away from FPTP voting, but getting that to happen in selecting electors is a reach (though at least the Electoral College means we don't have to do it nationwide at once).
Regarding Hillary in particular, I think an overgrown security apparatus is the biggest threat this country faces, and she has decisively lost my vote with her self-serving and revisionist account of the Snowden affair.