I chose Luna's story. I need it for FFXV to be the very least complete. That is just a story part that is necessary for me and I hope it will go through multiple chapters. If some of the moments show her as playable for us, sure, why not.

My number 1 is:

Lunafrena/Lunafreya's story, also liked with her being playable but it is not the important part

Then other story parts that are not necessarily Ardyn. Also World of Ruin if it is both story and running around doing something.

And then the rest.