A Wereraven, since those are already a thing in the Forgotten Realms lore where BG3 is set, and there's never enough love for bird-folk in any game. We only ever get furries and scalies. But since Larian never even gave us basic werewolves as a playable option despite their insane popularity, fat chance they'll give us bird people.
https://forgottenrealms.fandom.com/wiki/Wereraven![[Linked Image from static.wikia.nocookie.net]](http://static.wikia.nocookie.net/forgottenrealms/images/f/f4/Wereraven_5e.png)
Playable harpies would be pretty cool too.