If I was American I would definitely be voting for Johnson or Stein. I couldn't in good conscience vote for either of the major party candidates.
As a libertarian for the past 6 years I obviously support Johnson but he will never win. Best thing he can do is pull a Ron Paul and be seen as a moderate republican with a decent fiscal policy.
I'm not under any illusions about Johnson's chances of actually winning, but given that I am unable to support a candidate with a chance of winning I might as well support one who is closest to my views. There's also the (possibly naive) idea that if a third party candidate gets a significant showing of popular support, mainstream candidates might tailor their positions to appeal to that base to some extent.
In what world is Trump/Pence better than Hillary Clinton, unless you actually agree with Trump and Pence's political views?
I'm voting for neither presidential candidate, nor the third-party ones. I will only vote for the other offices in November.
Why not vote for a third party? Or do you just not agree with their policies in the same manner as the front runners?