I got Joanna outpointing her to a pretty clear UD. Zhang has never fought anyone with Joanna's ability to move in and out at different angles, pivot off the cage, and throw combinations fluidly and freely. Her distance management is very good, and I believe that's what Zhang is going to have trouble with.
Also, one thing that I don't see many people discussing is how Zhang has never gone five rounds, while that is essentially Joanna's highway. She knows how to dig deep in those final, championship rounds. Not saying Zhang can't, just that we've never seen it.
Of course, Zhang could bulldoze her in the first round and make me look like an idiot, but I do like Joanna's chances in this one. Good stylistic match up.