Clinton might be saying many crazy things but he is fundamentally a business man not religious or idealistic person.
Also, what is this "power vacuum"that you're talking about? What are you trying to say, that if Obama was militarily more aggressive, there would be less ISIS? Weren't you just before concerned about Clinton wanting war? You can't have both.
I was extremely surprised how serious Americans take Trump as a candidate when it is so obvious the vast majority of his speeches are incoherent rambling around one or two talking points played for effect.
I mean, seriously? A wall between the US and Mexico? There is already a wall between the US and Mexico. The various specifications he gave at various points throughout the primaries are obviously figures he pulled out of his ass to paint a more visually impressive picture.
And a stop for Muslim immigrants is entirely on par for the course. Sure, any other politician would have been more nuanced and phrased it differently so it doesn't sound like it's religious discrimination but let's not pretend that racism is a new thing in the US.
Trump's campaign boils down to bar-room clichés: lazy, half-baked "solutions" to real and complex problems. None of that is likely representative of what he would actually do once elected. Just like none of the "shatter the glass ceiling" and "yay minorities" rhetorics actually represent what Clinton will do once elected.
And we wonder that Russia feels emboldened to push its geopolitical interests? Russia needs to do that, or risk being wiped out from the world stage by an extremely aggressive US.
Instead of addressing the issue, the US has been playing dumb by claiming that "don't worry mate, this is against Iran not Russia!"
Now, Russia plays its own geopolitical game too, of course. And you might believe that the US defence shield poses no danger to Russia. But you have to ask yourself, what does Russia believe? Because if Russia really believes the US is making moves to neutralise its nuclear threat, it's just a matter of time until it strikes, because like you said the alternative is to be wiped out from the world stage. Don't corner a rat. Very very concerning.
And this has been some ten years in the making, since the US withdrew from the Anti-Ballistic Missile treaty (which the US argued at the name was so that it could build its missile defence system). This does not seem conducting of stability in the world.
The problem with US foreign politics is that in the face of it they seem entirely ignorant of how their actions appear to the rest of the world (and what it might mean to their interests and how they would react to that).
EDIT: To clarify, I'm not saying the US was responsible for the entire Arab spring, but the Arab Spring and the mess it caused (when the initial euphoria had ended) are part of the fallout from the wars in Afghanistan and Iraq.
Did you mean Trump (not Clinton)?
So, tensions are bound to raise, no matter who is in the White House or in the Kremlin, simply because the arsenal is there, we have done little to get rid of it, and we have allowed the military complex to hold us hostage to a campaign of terror (I am talking about State Terror) swiping the world specially after the September 11 attacks.
And regarding Trump rhetoric: the only thing that differentiates him to other politicians is that he is able to say one thing and the opposite in the same sentence. But all politicians, continuously, say something in one moment, and the opposite in another, or say something, and do the opposite, including important issues.
So, Clinton saying "I would not use nuclear weapons, ever", is not reassuring to anybody.
Again: we know Clinton's stance on war and the Middle East, Russia and China. Clinton already holds a lot of political power in the US (just look at her campaign's biggest sponsors and the Clinton Foundation -- plus the entire thing with her having been the de facto blessed Democrat candidate since before the primaries even started). Trump is an outsider who has the majority of the country against him (the GOP is still reluctant to present him as "their" candidate).
Hyperbole aside, the POTUS is not actually an autocrat. There is still a large body of bureaucracy and checks and balances preventing the POTUS from doing as (s)he pleases. Clinton would only have to worry about the Republicans, Trump would likely have everyone against him at some level.
He's not innocent, but he's significantly less dangerous. He's controllable (recently he went so far as to suggest that he would cede most of his duties to his VP -- effectively just leaving the prestige and title). Clinton is not (she already has an actual agenda and is far more nuanced when it comes to manipulating people in her favour).
Don't get me wrong: I don't want to see either of them become president. I would have loved to see Sanders win the primaries (simply because to me as a European he felt like a healthy counterbalance to the usual American politics) even though I was certain one of the other Republicans would have eventually won the election. But at this point you're basically forced to choose between Chaotic Evil with no political support (i.e. built-in limitations to the damage he can do) and Lawful Evil with an entire body of politics behind her (i.e. a lot of paved roads).
I'll call your attention to "Should the US formally declare war on ISIS?"
There are no "boots on the ground" in Syria as per policy, but there are American soldiers wearing boots engaging in combat activity in war zones in Syria on the ground. Except as they're not officially "boots on the ground" everybody likes to pretend the US isn't actually involved in Syria yet.
And when it comes to the decision whether to actually send humans who risk their lives and will be held accountable if they screw up, or to just continue drone strikes or bombing raids with no public accountability unless a military plane is downed -- I will prefer boots on the ground any day. War is hell. Drone war just allows one party to distance itself from the hell it is engaging in.