Hmmm...
The thing with this is that WW's bracelets kinda laugh off most of the ki-blasts except for really powerful attacks like Final Flash. That said, she can still can dodge some of those attacks and what does hit her can be offset by her regen.
The main thing, however, is the sword. That sword will remain a problem no matter what and Vegeta has really no way of knowing just how dangerous it is. In fact, there's a decent chance that he may think that he can block it by using ki to harden his skin if, no, when he goes in for HtH. He'd been for a rude awakening and probably loss the limb he tried to block with. Shoot, depending on where WW strikes, she just might fatally wound him then and there.
In addition, WW still has her lasso, which will be useful in grappling or restraining, giving her another tool to use.
That said, I'm going to go Wonder Woman, extremely high difficulty. Their both around the same level of power and skill but Diana's tools (mainly the sword) and regen give her that bit of edge to tip things in her favor. At the end of the day, Diana's bracelets allow her mitigate the damage and rangecoming her way, her regen further mitigates, her lasso can help to bind him and then her sword remains as a consistent threat and a 'I win' button for all intensive purposes.
At least, that's my take on this.
