The deficit/debt, hands down. It's despicable that only the libertarians realize the YUGE dilemma we are handing to our children and grandchildren. Sure, Trump probably talked about it, but he proposes big tax cuts and spending increases with no real way to pay for them. Clinton talked about increasing this tax and that tax, but her plan was still predicted by independent analysts to increase the deficit significantly. (albeit by a lesser amount than Trump's plan). When I started thinking about whether I could vote for Johnson, his commitment to balancing the budget was a large attracting force.
It is a real issue, but smaller than having a planet to live on. Being drowned in debt sucks for sure, it's not as bad as being literally drowned. This is why I eventually Heeled for Her.
The dilemma is I live in the rust belt and I want jobs to come back here. If climate change didn't exist I'd be far more vulnerable to Trump's populist rhetoric on trade and opposition to classist latte liberals. I'm tired of everything innovative coming out of California and only trickling down to us
peons years after the fact.