You either believe in Democracy or you don't. Trump's ideas are relatively clear by now. He's anti-Islam, anti-immigrant, pro-war, etc. He isn't getting votes because he's charismatic; he's not charismatic. He's getting votes because there are a lot of people who want to elect someone who is anti-Islam, anti-immigrant, pro-war, etc. All of his other political vacillations are less important to his bloc, so they matter little.
It's an inherent fault of democracy, that we will fall prey to a mass of people who disagree with us without a substantive mass to counter them. So, when there is a popular figure who we disagree with, we will organize against it or fall under it. And Sanders may not hate Muslims, but there are Constitutional protections against a lot of what Trump would like to do, and not especially against what Sanders wants to do. Hillary is the closest moderate choice, but she's not going to dissuade any would-be Trump voters, and is only serving to split and later disenfranchise the Sanders voters.
I'm not voting for any of them; I vote Libertarian for a simple reason. If the government is smaller and less powerful, it will have less impact on my life when a shithead like Trump takes power.