#1 Becky Lynch
Ronda Rousey vs. Becky Lynch was planned to happen at Survivor Series 2018, as every champion from Raw faced its respective champion from SmackDown. However, after the Nia Jax botch, The Man could not participate in the match due to an injury and Charlotte Flair took her place —WrestleMania 35 came early in 2018.
But that situation played in Becky's favor now. It is probably one of the most awaited matches and interesting rivalries in WWE recent history: that is the main reason why this bout should main event the next edition of the Showcase of Immortals.
And in the case they collide... Who would win? I am not sure at all. The Man, at this day, is way more over than The Baddest Woman on the Planet and she could take the victory in the very first 'Mania main event headlined by women.