These charts were made from results of the newest Public Policy Polling survey -- done on March 27th and 28th of a random national sample of 677 registered voters, with a 3.8 point margin of error.
It shows that any of five different Democrats would beat Donald Trump if the election was held right now. The favorite though is Joe Biden -- who has a 14 point margin over Trump. The others are Bernie Sanders (11 point margin), Elizabeth Warren (5 point margin), Al Franken (5 point margin), and Cory Booker (3 point margin).
So, who is the favorite among Democrats? That would also be Joe Biden (see chart below). He has the highest favorable rating -- and the lowest unfavorable and unsure ratings. He has to be considered the favorite right now.
NOTE -- I wish they had included Caroline Kennedy in this survey. I think she would have scored right up there with Biden.