#1. Ronda Rousey wins

WWE has invested in Ronda Rousey as its top female star this year. That choice comes with good reason, given the degree to which she is established as a mainstream celebrity and credible real-life fighter.
Booking Cris Cyborg against Rousey does introduce a sense of drama in terms of Rousey facing a challenger who could believably take her in a shoot fight. That’s in addition to making good on a fight UFC and the sport of MMA more broadly never could—highlighting wrestling’s ability to deliver dream matches on the premise that everyone is working together to entertain rather than actually trying to hurt one another.
In the end, though, Rousey is both the bigger celebrity than Cyborg and the one proven to be committed to the pro wrestling craft. WWE would have little to no reason to book Rousey to lose, unless it were to set up her victory in a return match.