No Elf, No Dwarf and No halfling.
Okay, let's get the boring out of the way first. Going to have humans. You just can't get away from them
After humans, since I need eight other races I'd definetly put in Gnomes. I like them a lot and they fill in some needed niches.
Now, because I don't want to run out of spaces, I want to throw in two big ones that I'd say probably would need to be put in as new races. The first is a Plant-Folk race. I find it kind of fascinating to have a race of people that are plants. Lot of fun things you can do with that. I know DnD has a few plant-folk races, but I've never been super familiar with them and I'd want to be broad, covering tree-people, flower-people, ect. I have a story I'm thinking about starting soon where I came up with "Arboreans" so I'll use that.
Following that, a Beastkin race. I could accept them as shifters, but I'd really want to combine a lot of seperate "motifs" under one larger blanket. Get "tabaxi", "leonin", "minotaurs", "lizardfolk", "gnolls", ect all under the same category. It might be a bit messy mechanically, but I don't need to worry about that right now.
hmmm, five left.
Orcs definitely. I've done some cool things with orcs and I'd want to include them. They wouldn't have a really unique place at the moment, but I'd likely make them closer to goliaths in size and just yoink some of that pastiche to make Orcs just the biggest and scariest... except...
Goblins would be another, and I have a weird idea about Goblins stolen from "The Wandering Inn" that I've been adapting into various forms. Goblins go through three "puberties" in my mind. So, little green goblins "grow up" into Bigger less green hobgoblins who then "grow up" into massive hulking "Ogres". But all I'd take from the Ogres is the size. Now in this set up, I'd probably never make an "Ogre" a player character. They are definitely NPCs or the like. But it is a really cool idea, especially when combined with the Eberron Dar and their concepts of Atcha and Muut.
Dang, only three left.
I've got to have some version of Tielfings and Aasimar. They are more a modification on races than a pure race, but they help fill things out.
And then I'd have to take Warforged.
Honorable mention to #10 would be Changelings, because I am a sucker for shapeshifters, but they wouldn't really make a cut for "core"
So, TL;DR
Human, Gnome, Tiefling, Aasimar, Warforged, Orc, Goblin, Arborean (Plant People), and Beastkin (combining multiple anthros under a single banner. Or just shifters) That would be my line up of 9