Alright so the background ponies have all found their way into our hearts through the show, fanfic and youtube videos etc.
And you know them being being BG ponies will likely stay, so if a spin-off show or short series could be made about any of the ponies or multiple ponies which characters do you feel it should be about it?
I honestly would have to say Vinyl and Octavia, but maybe that would dissappoint people because of the peronality given to them by youtube channels and other work, so might be different in a bad way. Slice of Life was ok because it didn't really dig deep, but you know who knows. Maybe it's just Vinyl speaking if they make her speak unless they get Nowacking.
So if not them then I would have to say Zecora or Lyra and Sweetie Drops/BonBon (after the Spy reveal).
Also what would this show revolve around? Friendship? Magic? Etc.