Just saw this this morning and whilst there is no poll yet (will be coming soon and will be multi-choice), there are several comments and as of right now there are 22 of them including one from L&P and from myself. Of these 22 comments, 10 mention Dylan, 7 mention Ellie, 3 mention Sam, 2 mention Patricia, and Alyssa, Julia, Amber, Nathalie, Emma, Zara, Aiden, and Zac all get 1 mention.
If the poll, when it's posted, reflects the way these comments are trending, then it looks like Dylan and Ellie will come out on top in terms of popularity.
Keep in mind though that L&P said this in the comments:
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I'm hoping this means that, whilst L&P says it won't influence anything in the game, they might consider letting it influence how much certain characters will feature in future updates. For example, if Sam fails to garner a lot of votes, I would think that his events would be lesser and shorter than characters who score higher, which is looking like it will be Ellie and Dylan.
Hopefully this would speed up the production a little bit by not spending too much time on events for less popular characters and focusing on the popular ones more.