This doesn't quite apply to me, since I live somewhere with RCV and gladly use it. But:
A third party that doesn't waste my time by only running top-line candidates while ignoring every other aspect of the necessary political gains to achieve their goals. Especially when the planks of their platform are overwhelmingly in the hands of the house and senate and not in the purview of the one position for which they decided to lackadaisically run. A third party presidential win with no support in the legislature would doom any real progress that third parties could hope to achieve - giving us a figurehead with no means to enact their agenda would only dissuade voters from seeing future candidates as viable and locking us back into the same dichotomy.