So it occurred to me that one of the characteristics of Trump, Obama, W. Bush, Reagan and Clinton was a supreme comfort in their own skin combined with some measure of charisma (W. Bush being the exception, but he was running against Albert Gore and John Kerry so he looked like Elvis).
I wondered how to view this admittedly subjective metric with regard to the 2020 race (and 2016).
In 2016, of all the GOP contenders, those truly comfortable with themselves combined with some measure of charisma were: Christie, Trump, and Huckabee. Christie was fatally wounded by the bridge incident, and Huckabee never caught fire for whatever reason (some say that 2012 was "his moment", which he missed). I liked Rand Paul but I suspect part of that was simply that I liked what he was saying, which is sort of why so many liked Trump. My father-in-law said exactly that, that Trump was saying what he wanted to hear and that's why he liked him.
There's a very thick overlay between liking what you hear and liking the person. I see that with many Catholic priests who, for me, can be very dry and charisma-lite, but because they are talking about things I wholeheartedly agree with (even if in a trite way), I like them, feel a kinship.
So teleporting to 2020, my exposure to Democrat candidates is small given that what they say is generally nails-on-chalkboard. But based on the comfort in skin and charisma characteristics you could say that Biden and Bernie (and Buttigieg from what I hear) are extremely comfortable in their own skin. For that reason they could be formidable candidates for Trump. Biden and Bernie are Trump-like as far as bluntness, outrageous statements and insults, although the insults are more general than specific as in Trump's case.
My sense is that the easy candidates for Trump to defeat would include Booker, Warren, Beto and Gillibrand. I haven't seen much of Harris to even guess.
What's interesting is how when a party tries to win over the other side with folks who they think the other side might like, it mostly goes up in flames. Like McCain, Romney, Kerry, Gore. Gore was a Southern Democrat who didn't talk like Dukaksis. Kerry was seen as the calm alternative to the wild-eyed Howard Dean and was a military vet, which was "against type" given the liberal ethos. Romney of course set up health care in MA and McCain bucked his party maverickly.
All of them failed. Is Biden the "calm alternative" (to Sanders this time) like Kerry was - and thus a failure in the making - or is he completely different than Kerry since he's comfortable in his own skin and a friendly pol unlike the reserved New Englander Kerry?
A decent test is if a conservative can listen to someone from the other party and not be disgusted. I could listen to Clinton in 1991 and not be repulsed (that came later). I could listen to Obama similarly in 2007 (that came later). Bernie passes this test now with me, so by this metric Sanders is the most electable 2020 candidate. Perhaps in a perverse way the conservative's greatest friend may well be the DNC and the other Democratic elites who want anybody but Bernie.