If we're sticking with Fates/Awakening/SD...
Fates: Felicia maybe, either Selena or Beruka, and Kaze.
Awakening: SUMIA MARIBELLE AND CHERCHE PLEEEASEEE
SD: Idk, the characters super well so... yeah
If we were to get some other games, maybe Ike, Roy, Mist, Hector, Ephiram, Eirika, Micaiah, etc.
A sequel would be amazing