If given the option, which recent US presidential election would you flip?

Hillary, easily.

Obviously, I wouldn't want any Republicans to win that didn't. So those can come off the board immediately.

So that leaves:
2000
2004
and 2016

Gore at first glance seems like a good choice. We probably don't go into Afghanistan or Iraq. There's probably no patriot act.. but the ripple effect leaves a lot of questions. Two options here: A. We take the poll as a 'one flip, the rest stay the same' in which case Kerry beats Gore in a primary, and then Bush beats Kerry, and everything else stays the same. In which case we probably get something worse than the patriot act, and maybe still drawn into Iraq. OR we take the poll with a ripple effect, and we change this one, and potentially others. Meaning there's a risk for Gore to lose to someone worse than Bush in 2004, who... gives us something worse than the patriot act, still draws us into the middle east, and potentially wins a second term and gets 3 SCOTUS justices which is potentially the most dangerous thing of all. (Keep in mind that if this were the case, the SCOTUS makeup would be: Roberts, Scalia, Kennedy, Thomas, Ginsburg, Breyer, Alito, Republican, Republican. A 7-2 Conservative court, with at least two justices appointed by someone who did things worse than the patriot act. Too much to risk to pick this one.

Next up: John Kerry. Honestly, I think the ripple effect means putting off on Obama for a while, which potentially could lead to Trump not running at all. But it could also mean no president obama. And.. we might not progress toward Obergfell. On the upside though, Alito never makes it onto the court, instead replaced by a liberal justice. Still think it's a bit too risky.

Lastly: Hillary over Trump. Scalia gets replaced by... let's say Kentaji Brown-Jackson. Ginsburg gets replaced by a Liberal. Breyer probably steps down for a younger justice. The Supreme Court makeup is now 5-4 in favor of liberals. Probably the best outcome. Hillary handles covid better, and Trump's cult probably abandons him after he declares election fraud. They didn't in 2020 because he won in 2016. He'd still have some ardent followers, but... I think it'd still be a bridge too far and Republicans would pounce on him losing blaming him for "Queen Hillary" as they'd probably call her.