I'm probably going against the grain here, but unless we're going campaign-specific, I'd like less "fantastic creature" PC races/species/lineages, and divide humans in a dozen distinct lineages.
I guess I'd like to see more monsters-as-playable-races, humanoid versions of monsters (like half-giants for each kind of giant, and what would an ankheg-folk be like for instance?), and some races with more than two eyes or arms.
I thought there was an official Gnoll player race too. I think I was thinking of the write-up in Volo's, which is great but doesn't make them playable.
There are many many game systems out there that allow a player to create a char from scratch, like Heroes. It would be vastly easier for the OP to play that game, than changing the 5e system.