Well, the thing here is that the "two parties" aren't actors. The candidates who get nominated aren't "chosen" by the party leadership (or "establishment") the way they were in, say, 1932. It wasn't the Republican party establishment that elevated Donald Trump in 2016, and it's not the Democratic establishment that's pushing Bernie Sanders in 2020.
So we get nominees who really do reflect the popular will of large slices of the electorate. Yeah - Donald Trump and (probably) Bernie Sanders. And voters who are part of the "establishment" find both options to be at least somewhat irresponsible - because in one way or another, both options threaten the establishment. (Which appears to be exactly why these candidates appeal to so many voters - we should reflect seriously on why this is the case.)
It seems to be that given that choice, one votes for the option that is less dangerous. Now, we can (and likely will!) disagree about who that is - about whether a drift toward more "socialism" (social-democratic programs like MfA, free higher education, etc.), or a drift toward more "fascism" (corporate statism, money dominance of electoral politics, anti-environmental de-regulation, nativism, etc.) is the greater danger.
The only thing that is certain is that there will be change. There always is. Changes for the better, changes for the worse.
But here's a thought. I'm 66 years old now. I won't be here to reap the benefits (or the penalties) of many of the changes that will occur in the next few decades - the changes that will be driven (in part) by the choices we collectively make this year. Those of us who will have to live with the long-term results of the 2020 election seem to be coming down rather strongly on one side of this choice. Are they wrong? Do we just "know better" because we're older (assuming you're "older," as I am )? Or is that just ego talking?