The invention of the democratic republic requires the development of the institution of the political party, which mediates between the ruling class and the voters. One way to mediate is by political philosophy or ideology, but that's not the only way; the point of political parties is to explore all the different ways of mediation, and find the ones that are successful. The process is complex: there are struggles within the ruling class (and sometimes struggles between classes for rule) and struggles within the electorate, and all the different forces are partially reconciled in the political parties.
The electorate can more-or-less "passively" accept its role: the political parties position themselves in relation to the ruling class and the electorate, and each person picks the option they like best or dislike the least. If we take this view of the role of the voters in a republic, then Hillary Clinton is the best choice for everyone who has not yet been completely screwed over by neoliberalism, and Donald Trump is the best choice for those who have been completely screwed over by neoliberalism: they're screwed anyway, and Trump might at least shake things up and create opportunities. (Trump is the best choice for racist assholes regardless of class, but that's a side issue.)
I don't like this view of the electorate, which shouldn't come as much of a shock. I have two alternative views. As a revolutionary communist, elections are just one of the many arenas of struggle to develop revolutionary momentum. Presently, revolutionary momentum is at best miniscule, and at worst backwards, so the upcoming election does not offer much to be gained or lost in this regard.
As a progressive reformer (and I can be both, why not?) I urge a somewhat more active role for the electorate. The voters are negotiating: they are actively trying to change the character and nature of the parties and the nominees. In order to negotiate, a participant absolutely must convince their opponent that they can walk away from the table. If the car salesman knows that I absolutely must have a car by the end of the day, I'm guaranteed to get screwed. She knows I can't walk away; she need only make sure it's not impossible for me to sign.
As negotiators, we absolutely cannot say that we must vote for Clinton because Trump. Instead, we must convince Clinton and the Democratic party that if we don't get enough of what we want, we will walk away from the table, Trump or no Trump. When we say Clinton because Trump, we are saying to the car salesman that we must have a car by the end of the day. We are begging Clinton to screw us over once she's president.
Of course, as negotiators, Clinton and the Democratic party, to serve their capitalist masters, must argue that we must vote for Clinton because Trump, to convince us that we must have a car by the end of the day, and thus concede as little as possible to the electorate. Hillary Clinton would love to go to Wall Street and say, "I delivered your agenda."
Scary, no? But that's how negotiation works. It's a pure strategy chicken game. And if you credibly promise to swerve, you will lose every time.
So I don't give a shit whether Jill Stein is or is not an anti-vaxxer. Jill Stein is not going to become president, and the Green party is not going to be a major player; if they were, I would actually participate in the party and remove the stupid from the platform.
The point is that I will vote (because not voting is dumb), but I'm going to credibly promise to not vote for Clinton if she doesn't promise to enact a progressive agenda, not just a less regressive agenda than Trump. And if Trump does become president because Clinton doesn't come through, well, presidents don't have absolute power, and there are ways to limit and resist Trump's power (cough Bill Clinton cough).
Progressives should want Wall Street to say support Clinton because Trump, that even though Clinton had to seriously compromise the neoliberal capitalist agenda, Trump would have been even worse.
So when you tell me to vote Clinton because Trump, or that I'm "wasting" my vote if I don't vote for either Clinton or Trump, you're telling me that you'll let Clinton promote whatever neoliberal horrors she chooses, because she knows your vote does not depend on her policies.
If we can't have a revolution, let's at least negotiate, not bend over.