#4 Liv Morgan should win because another loss may disrupt her momentum
As mentioned before, Liv Morgan lost to Becky Lynch on an episode of RAW. As popular as The Man is, even as a heel, the crowd was behind Morgan on this occasion.
They were rooting for her to defeat the big bad heel, to realize her destiny, and capture the RAW Women's Championship. If Liv Morgan comes up short again, against Becky Lynch at WWE Day 1, it may curtail her momentum.
#3 Becky Lynch should win because there are better contenders waiting in the wings
Fans may feel strongly about Liv Morgan at this point. But they may be more firmly behind someone like Rhea Ripley or Naomi, winning the Royal Rumble and defeating Becky Lynch at WrestleMania 38.
Alexa Bliss or Asuka could return at the Royal Rumble too and go on to win the entire thing, to challenge Lynch at WrestleMania. Both of these prospects may be far more exciting than Morgan becoming the RAW Women's Champion at this particular point.