I have just started the Episode Freya book and so far I'm loving it . I also really enjoyed the Lyuu/Ryuu book but she is easily my favorite character. So that got me thinking of who else would I like to see get their own familia book these are a few of my picks
1.) The Ganesha Familia. I think he is a much deeper character then you get see especially if you only watch the anime. I love his up beat personality. it is very clear that he loves not just his familia but all the people of Orario. You do get a few glimpses of there being more to him in the books like in the Xenos arc where he is talking to Hestia and tells her that if a day where the Xenis could coexist he would become NeoGanesha god of man and monster. I think he is an awesome an under appreciated God.
2.) The Hermes Familia. Yes we do get to see a lot of Hermes in both the main series and SO but there is still at that could be covered in a stand alone book. Like his link to Zeus, or How Asfi joined his familia or more back story or side story for Flagar and Lulune. Even just tales from some of his adventurs outside of Orario considering he is basically the only god that can freely come and go from Orario. He could even be a good way to interduce new Gods and Familias to DanMachi
3.) The Demeter Familia. Not much is really know about her well least from what I have read. I will admit I have only read what in out in the US I still need to read DM 15 & 16 and SO 12 with 15 out in a week or so ill knock it out soon. But I think this could be a cool way to show a slice of life for a non adventuring familia and how day to day life runs in Orario. We could also get some stories from Lunoir's days as a bounty hunter before the Ryuu book or she could get pulled back in to it somehow. I see lots of potential to a book like that
Those are just my top three picks I could keep this list going all day but this post would be so long no one would read it . LOL I would love to hear what you guys think and what stories you would like to hear.