Democrats are still better than the alternative.
Voting for a third party candidate in this system is ignoring the plain and simple fact that third parties are not accepted in political discourse here. Yes, its a horrible fact, but its a fact. Until you manage to affect some sort of change, that is the reality you live in.
And even then, what will it really change? For the large part, a vast majority of America will just vote for the parties they know, even should you make a miracle.
Just because Jill Stein or whoever says some nice things, doesn't mean they're gonna get anywhere in the Presidential Race.
If you want some of the progressive plan put into place, you have to vote for the Democrats, or you get the Republicans who will only set things back.