Personally I only see Bernie winning, though I can admit that both Yang and Tulsi's crossover support make it possible for them to beat Trump as well. Everyone else is just setting trump up for re-election sadly.
Talking out of my ass of course - and also looking at tons of info, rhetoric, and opinions from people all over the political spectrum (and probably also personal bias too admittedly). But I pretty much agree, I honestly think Yang and Tulsi have the best chance to beat Trump by far. Why? B/c they have crossover support. That is what you need to win elections.
Sure, you could say the general is a different story but the end game is to beat Trump, right? It's going to be tough to inspire a high voter turnout for Centrist corporatists like Biden, Warren, and Buttigieg b/c many will ask themselves, well, what's the point? You could argue the point is to beat Trump, but what exactly, on a fundamental level, is the drastic alternative these centrists are offering that's so different and improved from Trump in the first place? Especially with a guy like Biden who literally insults his own voters, has a ton of baggage, and is basically a Neocon running as a Dem, or Pete who can't even commit to M4A or loan forgiveness, and claims he won't even meet with our adversaries when even Obama was on record saying he'd be willing to do so.
Bernie definitely has a chance to win - mainly b/c of the Rust Belt/Mid West, which, as a Midwesterner, I can tell you, Bernie was FAR more popular here in 2016 than Hillary, thanks mainly b/c of his opposition to trade deals which have screwed over our economy. Still, I do think Bernie will have a hard time shaking off what many perceive to be a farther left "socialist" angle which many in America seem to fear. I'll admit, he's a bit far left for me, but I'd certainly vote for him and still very much prefer him to both Trump and Neolib corporatist candidates. He'd almost certainly draw more voters than Hillary, and still appeals to some independents, though might turn off some moderates.
Yang and Tulsi are more interesting - as they're both more outside the political establishment, and come off as moderates in some ways that draw crossover support, while at the same time many of their ideas are actually pretty significantly left wing and seem to offer real positive change. They also tend to be more grounded in modern day society and more in tune with the issues facing young people, especially Yang. This is why I think they'd be the best candidates to beat Trump.
Unfortunately, the media is a powerful mechanism that can easily sway millions of minds. Hell, they've convinced millions upon millions of people that Tulsi, the progressive vegan woman of color from Hawaii, who plays the ukelele, serves her country in the National Guard, and advocates peace, is somehow a "traitor," "dangerous," "supports dictators," a "Russian Asset," or a number of other preposterous fearmongering garbage. She was once the Democrat darling and future prospect but as soon as she supports Bernie and goes against the Clinton machine she's suddenly evil incarnate. This is the power of the MSN to manipulate people's minds. It's not easy to overcome that level of power and influence.
While their influence is declining, I do fear that between their reach, and that of the Dem establishment who clearly does not want these two in their party, that they won't even have a chance to be the nominee in the first place to beat Trump. But I do honestly believe the Dem establishment are ironically a bigger threat to Tulsi and Yang than Trump is.
The only REALISTIC hope to beat Trump at this point is Bernie, which he could definitely do - though we'd have to see it he still has the Rust Belt like in 2016.