Ok, since it seems like people have been mostly picking stages arbitrarily..
The reason why I wanted you all to have the option to put in your stage requests, is NOT to randomly request a stage for no reason aside from they like the stage number or things like that, because if you have no good reason then you'll probably be arbitrarily assigned based on where you seem to fit the best.
Like for example, Xan is Stage 6 because she's Theorin's maid. Matsuri and I have some kind of vague relationship in game, and we both have the pet things, so she fits in S6 too. Skye is a bird type, and the first two stages are going to be outdoors and in the open, so she would fit there the best. (Note Skye had no preference, and I just figured out where she fit)
This is not an exact science. N-Forza is a Special Member, and also occupies a special niche in the MotK community, which to me seems like he would fit in OMES. Also, N-Forza --> Bemani --> OMES, it fits. If you have any sort of relationships or associations with the bosses, midbosses, or whatnot, that makes it more likely you'll fit in with a certain stage. Some embodiments are more loose than that, and could fit in multiple stages. They don't all have to fit perfectly due to the backstory of the embodiments, but it's nice to not have things be completely random either.