[erimir]

Currently, I would order the declared candidates as...

Warren
Gillibrand
Harris
Castro
...
...
...
Gabbard

Not going to bother with Ojeda or Delaney.

Adding in some other likely/plausible candidates, and sorting into tiers:

I'm fully on board at the moment:
Warren
Gillibrand

I like them, but they have some issues I'm concerned about:
Harris (prosecutor record, need to know more about economic agenda)
Booker (charter schools, Wall Street issues)
Bill de Blasio (not sure he could win?)

Much bigger issues:
Biden* (too old, various issues with his record, generally too centrist)
Sanders (too old, I don't feel like he would be an effective leader since his colleagues don't like him and his 2016 campaign had some serious organizational issues)
Brown (I like him, but I'd need to be convinced that he is amazing to make it worth it to give up that Ohio Senate seat, because the GOP governor appoints his replacement and Ohio is red-leaning and it will be very difficult to win the seat back with a Democratic president)

Don't really know enough:
Klobuchar
Inslee

Don't seem like great choices, lacking experience or a high enough profile, so they will need to really impress me:
Castro
O'Rourke
Oprah

NOPE:
Cuomo (just putting him here for good measure, he's probably not running)
Bloomberg
Gabbard

*And with Biden, I'm only somewhat curious because he does well in polls vs. Trump now. This could just be due to name recognition and I'll be surprised if his polling advantage holds up through next year. But it is definitely relevant. If Biden can win by double digits, and Warren can only win by 6 pts, this matters, because a double digit win basically ensures Democrats take the Senate AND won't need Joe Manchin to be the 50th vote on everything. Warren has better priorities than Biden, but if you want to pass, say, DC statehood or Medicare For All, Democrats will want to have some wiggle room. Especially since even just getting rid of the filibuster so you can pass any of that will take some convincing.

But if Biden's polling advantage vs. Trump disappears, he drops down into the bottom tiers.