It seems that there is a contingent of voters who want to see Gwenpool win, be it due to legitimately liking the character/her design or because of the meme status of the character. There also seems to be a contingent of voters who steadfastly oppose letting her win, and will rally behind whatever option seems most likely to beat her. There's also a smaller portion of voters who just like the other available options, and will vote for them regardless, potentially dictating the option of the anti-Gwenpool voters. So far, the balance has been in favour of the anti-Gwenpool voters + whatever non-Gwenpool faction is getting supported by them. The wildcards for future votes is voters leaving, new voters joining, and most likely to be relevant, the choices of the non-Gwenpool voters who had their option win previously, as they could potentially join any of the factions now that their previous preference has won.
Fairly certain Oni has previously noted he does not plan to add Mystique, due to how her shapeshifting ability would mean having to do multiple looks for her, alongside her potentially being able to change into other characters and generally needing to decide how to handle all the various issues involved if he were to add her. Basically, as a shapeshifter, she'd take far more work to implement than most other characters.
Of the options available, I'd personally be curious to see Wanda and Lorna win (in either order), mostly as I'd be curious to see if Oni would add any scenes or dialogue that makes note of them being half-sisters. Admittedly I'm skeptical of how much would be done with that (both due to Oni's general manner of adding things, and the fact that while they are half sisters, they weren't raised together, nor did they seem to have much interaction in canon that I know of).
Of course, there's also the chance of a new girl or two being added to the list for next time, but I'll not bother to speculate on that.
