Supporting the lesser of two evils when no other option stands a realistic chance is equivalent to minimizing the likelihood of being stuck with the worst of the two outcomes. That is a rational choice, regardless of whether it’s a truly moral one. In that case, it’s only a better choice (your words) if you value your moral standing over the actual consequences derived from the worst candidate winning (and if you do, it might imply that the outcome of this election has very little effect on you at the personal level).
Supporting a third choice with no realistic chance of being the collective result (unfortunately, the world isn’t always fair) increases the potential of the worst outcome — which is the worst depends on each person’s point of view and I’m not making any judgment on that. From a pure scientific viewpoint, that would not be a truly rational decision.
If your state is heavily red or blue, it’s your vote and feel free to take a stand or make a statement. But if your vote can play a relevant role in the election (i.e., a swing state), make sure the choices you make reflect not only your moral upside for taking a stand against the establishment, but also the expected collective social downside of removing one vote from the lesser of the two evils. It’s only “better” if you factor all of that. Collective decision making is not necessarily equivalent to aggregated individual decision making.
Not all Americans can afford the luxury of taking stands with votes. For some of them, it’s their future at stake. Take care.