#1 Charlotte Flair
Remember when last time WWE had the odd rule of letting the women's Rumble match winner pick the champion she would face, irrespective of which brand she was on? The same could and most likely will come into play this time as well.
Charlotte against Ronda has already been more than teased at Survivor Series, and it most likely will happen at Wrestlemania and even possibly headline it.
If this were to be true, then there is no other alternative other than having Charlotte win the Rumble and choosing to face Rousey. Also, with Flair's recent heel turn, Ronda and Charlotte are to the women's division what John Cena and Randy Orton respectively were to the WWE a decade ago.
WWE is going to invest heavily on these two women going ahead and that is why they have been protected so well up until now.