Will likely be Wes Streeting or Rachel Reeves.
Labour need a woman leader at some point so that gives Reeves a big boost, but Streeting would presumably be first (openly) gay leader of a major party (unless I am forgetting one) and is better on the media and a better speaker.
If there was a Rachel Streeting, she would be a shoo-in.
Burnham has lost what momentum he had. His moment has gone. As his music choice showed, interestingly enough
https://thequietus.com/articles/31215-andy-burnham-bakers-dozen-favourite-music. Solid, but stuck in the past, inward looking and unadventurous.
Yvette Cooper is tremendous in the Commons so has a chance.