I had a political theory professor whose interests mirrored yours (Nietzsche, Frankfurt School, Hegel, etc) in undergrad, and he always struck me as belonging in philosophy. Let's face it - in a PoliSci department, you're going to be a lone wolf; everyone will be doing studies on vote turnouts, intl. systems theory and micro finance and you'll be in the corner talking about the Owl of Minerva. PoliSci undergrads will be flummoxed by what you have to say (at least we were in this guy's class - Contemporary Political Theory and we read Nietzsche, Beckett, Camus, Sartre, Marcuse, Adorno, and de Beauvoir).
Pol Theory as a discipline might promise better job prospects, but you'll have better job prospects in philosophy with these interests, IMO.