Well, one per each game is a pretty easy pick.
Shadow Dragon/New Mystery: Sirius (Cause badass Camus is badass) or Samson.
SoV: Deen. C’mon man. Deen’s a badass. Get him in here already.
FE4: Can we talk about Ced? Like, we got Seliph, Leif, and Ares. Where’s Ced?
FE5: Well, Sarah I suppose is one I’d like.
FE6: Igrene or the Wyvern gang. Forget their names.
FE7: Probably any of the Morphs. Sonya, Ephidel, etc, etc.
FE8: Corrupted Lyon would be best IMO, but I’ll take Natasha. Joshua needs his queen.
FE9: Ashnard. Cause Duh. Where the fuck has he been the last 3 years or so?
FE10: Well, I’d say Zelg but he’s already in. And Ashera-Ashunera are shoe ins eventually. Soooo, let’s go with Rafiel. Round out the bird trio.
FE13: Well, I’d say Teach (vaikester), should get in already. Teachers are popular now in FE anyways.
FE14: Well, Charlotte for starters should get her regular version in already. And if they’re afraid about her clothes being too much, then they should’ve thought about that early on when they designed both her and Camilal (fucking Maeda man).
FE16: Well, pretty obviously I want Dorothea. But runner ups are Caspar (boy wants to blow up someone with his fists), Ferdinand Von Aegir (I have to say his full name, K), or Lysithea.
But overall Dorothea if I had to pick one.