I'm trying to envision how this fight actually goes down. They start from a distance away (100'). WW is going to close for sure since she has no major ranged attacks; BRB might close but might also attack from a distance. However Diana can close that gap pretty quick, her running speeds are extremely enhanced and well documented, and in character. Let's say she closes and he attacks from a distance. He's not going to go all out in a generally populated area on his first attack. And I'm pretty sure she's going to dodge or deflect those attacks through speed and agility. They're not bullets, but being able to deflect machine gun bullets with your arms means having ridiculously good reaction time, and that applies to dodging as well as deflecting. So one way or the other I'm pretty sure she'd going to end up close to BRB and without major harm.
Close up, she has way faster tactical moving speed and reflexes. They can both fly at enormous speeds but I am highly doubtful that he has the aerial mobility/agility she does if they take to the air. I'm assuming no sword as it's not standard equipment regardless of whether it existed or not pre-52. She's not going to have much luck damaging him with pure punches or kicks with his durability, but her speed is going to allow her to land a bunch of hits. Also, she is a martial artist and wrestler as well as a brawler and she's going to use those skills to attempt to immobilize on him in the same way she has in her numerous fights against Superman, Supergirl, and Power Girl. Meanwhile Bill is going to melee right back. I think Bill is more skilled than Thor, honestly, he is a tactical fighter, but he's just not at her level. He's going to probably do more damage on any given strike than she would, but he's going to have a harder time hitting her. But in the end I don't see either one taking a win from this phase of the fight. Both of their many battles against other heavy hitters give me no reason to think they can easily defeat the other, or be easily defeated, from brute force.
At some point, all discussion of planet busting aside, the two of them are going to decide that melee isn't going to hack it. Diana is eventually going to go for her lasso, maybe sooner than later. Bill is going to add lots of energy blasts and at the very least massive winds to his melee fighting, maybe sooner than later.
At some point, one of those two tactics is going to beat the other. At this point I still can't decide who goes down first. I am leaning toward too close to call.