Why not Gary Johnson?
Half the country hates Trump, the other half hates Hillary. Nobody really hates Johnson. So far, Gary Johnson is the only one that I actually don't mind. I haven't decided who I will vote for, but he's at the top right now.
People say he can't win, but that's not true. He won't win 270 electoral college votes, so people think he can't win. But you have to understand how our elections work. All he has to do is prevent either other candidate from reaching 270 electoral college votes. He can ostensibly do that by only winning a few states (which isn't outside the realm of possibility, look at Utah for example, three way tie in some polls...).
If he is successful in blocking a 270 election, Congress (the sitting Congress, which is Republican-leaning) elects the next President and VP separately.
The House elects the President from the top three candidates (which would likely include Johnson) and the Senate elects the VP from the top two VP candidates (likely no Weld, his running mate).
I posit Johnson would be the best overall candidate that the majority of Congress could actually agree on. Is this outcome likely? No. Is it possible? Certainly. Many people (as you can tell with the rise of Bernie and Trump) are sick of "establishment" politicians and want something different.
Because really, if you think "vote your conscience" is an insult to your candidate of choice, you might want to rethink your candidate. I'd rather vote FOR someone than vote AGAINST someone.