The choice between these two options: the futuristic/alternative urban utopia/dystopia with a youth, coming-of-age emphasis versus the fantastic past mystery of where is Bruegel, what happened there, who was responsible, and what can be done to un-happen it.
Genre-wise, these sound like (a) a young adult/coming-of-age science fiction adventure, and (b) a fantasy history detective story with some focus on children (the massacre of the innocents). Which am I most interested in writing, which am I most capable of doing, and which would appeal most to readers, assuming that I could pull them off.
What are the research demands of these two projects? The demands of Bruegel seem larger, though that could be an illusion.
To answer question 3, the first project has potentially more readership appeal because of the relevance of some of the underlying themes, and the possibilities of the characters. Also there are possibilities for multiple volumes, since all is not likely to be resolved in one.
I think the Danikiiwin story has more appeal to me as a writer, and probably as a reader. I think it would be easier for me to write because I would understand the genre and the potential readership better than in the other, which I think would require more skill and practice to deal with the complexity. This first one is more simple.
The decision (provisional) is for Danikiwiin.