It is not uncommon for publishers and developers to ask their audience to tell them what they like about a game or a franchise. In the case of Square Enix, they’re asking their fans to reveal via a survey which franchise they would buy first if they came out on the same day, Final Fantasy or Persona.
“If Persona 5 and Final Fantasy XV were released at the same time, which would you prefer [to buy]?”
Though the reasoning for the survey isn’t exactly clear, it is logical to believe that Square is looking to fans to determine which game will release first, Final Fantasy XV or Persona 5. Both are popular franchises in Japan, and likely Square Enix is wishing to determine which would sell better earlier, and how far apart to have the two releases.
Both games are coming in 2016.