It's likely to be Andy Burnham, who IIRC is currently the only British politician with a net positive approval rating. So that's something. 🤷♂️ He's been pretty successful (and well liked) as the mayor of Greater Manchester, and generally comes across a bit more human than the other lizard-people in British politics.
He's often described as "soft-left" by the media. So far, he's been a vocal supporter of proportional representation, which is great, but whether he'll drop that as soon as he gets into Number 10 is a different matter.
He's a member of the "Labour Friends of Israel" group, but kinda seems to mostly sit on the fence on that whole issue. (He called for a ceasefire but refused to call it a genocide.)
I'm sure other people will chip in with other problematic things about him, I haven't looked too deeply. 😃