The currently remaining Democratic candidates can be grouped by numerous attributes, most notably by their political leanings (far-left/left-of-center/centrist/right-of-center). These are mine.
The Known Commodities: Joe Biden, Bernie Sanders
When people are scared, like Linus van Pelt, they grab their security blanket. Known commodities, likewise, are what people pick when the unknown scares them. It's why incumbents have a psychological advantage over challengers, even when the incumbent is poorly rated. Take Mitch McConnell, for instance. They keep electing him but he's one of the least-liked senators, as polled by his constituents. Democrats are fearful of a 2020 win by Trump, so, they run to the known commodities early on.
The Brave Bet: Elizabeth Warren -- my first pick since 2015
She's smart, she's well-accomplished with her ground-up construction of the Consumer Finance Protection Bureau, and she's well spoken. She connects with most Americans, speaking to their economic fears. I truly don't believe a person understands economic insecurity until one's been there. She's been there, which is why her message is powerful. Yet, as Bernie Sanders suggested, America won't elect a woman. That is not to say that America can't/won't elect a woman, but that too many Americans harbor lingering doubt that a woman can lead this nation. Misogyny exists.
The Backup Plan: Amy Klobuchar
She's a lot like Warren, but not nearly as accomplished. Though she leans to the right of Warren, she's still significantly more liberal than any other Republican in the Senate. She is well-spoken, intelligent, and she's got a great background, but most of all, she comes from the midwest and can pull votes from the region. Still, she's the bench warmer. If you want the superstar, you pick Warren. The NYT's dual endorsement essentially highlights Klobuchar's backup role. Note how they mentioned Warren first and dedicated more space to talking about Warren. Warren simply has more accomplishments than Klobuchar.
The Rookies: Pete Buttigieg, Tom Steyer, Andrew Yang
Let's face it, being mayor of a city with a population of ~102,000 doesn't exactly establish your leadership cred. Buttigieg may be smart and well-spoken, but being mayor of a college town means you're a rookie in government. Steyer and Yang, having never governed, are in the same boat. These are the choices when you're desperate for change. There simply isn't enough information to understand how effectively they'd be at governing.
The Dark Hor$e: Mike Bloomberg
His billions and his political leaning (targeting the same centrist position of Biden) make him a dark horse candidate. The money ensures he'll be able to stay in the race and withstand low delegate counts, until the pool of candidates shrinks. At that point, he could gain significant attention in the media, pulling support from Biden and Buttigieg. Momentum at the right time means he could overtake the field.
The Hell Freezes Over Pick: Tulsi Gabbard
She'll sue anyone in the Democratic Party for talking smack about her, even if they're not talking smack about her. She's the self-defeating-do-anything-to-get-attention-because-the-money's-running-out candidate. Also, aligning herself with Trump was a non-starter. She's quickly fading nationally and at home. Even before she dropped out of running for re-election for her House seat, she'd already garnered a strong challenger from the Hawaii Senate. She's just not well-liked.
The Unknowns: William Bennett, Deval Patrick, John Delaney
Nobody knows them except for their constituents.In the debates, Bennett and Delaney slowly faded into the background of the debates and on issues, such that no one remembers who they are. The media won't cover them because they'd already faded into the background months ago. Still, they persist for no good reason.