well, let's look at some issues.
1) foreign policy. i think trump is an isolationist (although it's hard to be sure), where as it is clear that clinton is an interventionist. clinton *will* launch more wars in the name of the glory of the american empire. trump? that's less clear, and i think there's an argument he might pull back a little. ultimately, these are hard fights to win. civilian military control in the united states isn't really, actually a thing. it's not at all clear that he can convince the generals, if he'd want to. but, trump at least provides some hope of a reversal of imperialism. clinton represents the absolute status quo. sanders beats them both on foreign policy, but trump beats clinton.
2) trade. well, they're both claiming various levels of opposition to the expansion of "free trade". clinton has no credibility. remember: her husband campaigned against nafta. trump might very well put up some tariffs. again: sanders beats them both. but, trump provides more hope for some break in the status quo than clinton does.
3) health care. this is actually an important issue in canada. sanders is the best on health care. clinton supports the status quo. it's not clear where trump really stands. repealing obamacare is a populist issue in the united states, so he's taken that position. but, trump spent years supporting single payer, too! again: there's some hope that trump might bring in single-payer. clinton didn't take all that money to attack the insurance lobby with.
4) that wall. it's going to lead to inflation. i...i don't think he can really do this. but, clinton has her own albatrosses. i've been vocal about libya. they balance out.
5) xenophobia. see, this comes down to the question of how big you think the difference is. are the democrats really better? they're less obnoxious, perhaps. but, look at obama's record on mass deportations. i don't really see a difference.
i'm a staunch leftist. but, that's kind of the point: trump seems to be really running a good deal to the left of hillary, who is running essentially as a republican. it's hillary that seems like she wants to uphold the legacy of reagan, and trump that seems like he wants to blow it up.
i'm not endorsing trump. i couldn't imagine voting for him. it's just not clear who the lesser evil is.
i'm still rooting for bernie and hope he can pull it off, but the writing is on the wall. so, notwithstanding some come back by bernie, i'm going to officially endorse non-voting.
non-voting sends the message that neither option is acceptable. trump might win - but it's not clear he's worse, and he might even be better. but, if we can collectively pull voting below 30%, it sends a strong message of discontent. that is the most activist choice in this cycle, as far as i can tell at this point.