Ogion, Obama was pretty far left, definitely left of Clinton, in 2008. He went more moderate in his first term in order to have leverage on healthcare, which is what he wanted most. This is extremely well documented and anyone that has studied his policy knows it. In his second term, especially recently, he's gone back to being the center-left candidate that he was elected as. Hillary is centrist at best and corrupted regardless of her political stances, something Obama at least appears to have largely avoided.
Her record on the environment is two-faced. Prado already pointed that out. She is a worldwide advocate of fracking and a friend to fossil fuels. She takes on coal, which is great, but so does every Democrat. She is nothing new, and the environment needs something new. She, unlike Trump, won't gut the environment, but she will simply make us wait for someone else to come in and actually make progress on it like Obama has. I will be pleasantly surprised if she is as overt about protecting the environment as Obama has been.
I'm not voting for Johnson. The majority of his views are nuts. He would rather let regular people like you and I get eaten alive by some combination of insurance companies, corporate sellouts, and Sheriff Joe.
If the choice were Trump-Hillary, the choice is beyond obvious. I live in Indiana, so if I vote for Hillary, my vote still goes to Trump. If I vote for a third party candidate who even has a shot in the dark of hitting 5% for funding or 15% for media attention, then my vote actually counts for that candidate. If Indiana were a swing state, I would happily check the "not Trump" box, but it's not, so I'll vote green even though Jill Stein is a bit of a crackpot and hope that my vote and others around the country benefit the growth of the party as a national option.