I voted Kovalev. If (and that is a big if) he actually bothers to train for a fight, he is still the best current LHW.
I think overall it is probably Gvozdyk. He's got the tools to beat everyone else. But he can be hit and seems to suffer from temporary lapses in his game and that could prove disastrous against Beterbeast.
He hasnt beaten anyone in the top 50. Anyone rating him has to go based on the eye test of seeing him plug guys between 50 and 200 in the world. That means he is unproven- no one knows how good he is until he steps up and faces a higher standard of opposition. Bivol and Gvozdyk need to face each other in order for us to be able to determine the number 1