I honestly don't care who's important so to speak. To me it comes down to personal taste. But trust me when I say although I'm unfamiliar with AC, I would still rather have Isabelle than yet another Pokémon or FE character. And I'm actually familiar with those two. But man I feel like they're just going to keep stacking and stacking because there's various gens that people expect to see represented. IDK, it just gets pretty unsurprising. Like the smash 4 characters from those franchises while unique, where just eh, not exciting to me.
Though I will say it would be cool if they revealed an older character for FE in particular, same for Pokémon. Though I feel like Inceniroar I'd be fine with. I also saw Blaziken suggested as an Echo today and eh, I would prefer Blood Falcon if we were to get a Falcon echo. As we have yet to see echoes of various series, as that'd be weird on the roster I'd imagine. Maybe I'm wrong.