Stroker, Gray, and Testa are locks right now.
The final 2 slots could go to any number of talented women: Stephanie Styles, Sarah Stiles, Leslie Kritzer, Lilli Cooper. I don't think anyone else is a legit threat. Hatred for Beetlejuice helps the Sti(y)les sisters; genuine love for Tootsie helps Cooper & Stiles; and rave reviews for Kritzer could help get her over the edge.
In terms of a win, Stroker really "pops" in Oklahoma!, and she's the most conventional musical comedy performance in the production; even if they don't like the production, almost every critic liked her. (Case in point: Terry Teachout in the WSJ.) If voters LOVE Hadestown and are only going to give Oklahoma! the obligatory Best Revival win, that could tip the scale towards Gray.