I am going to choose Sobble as my starter and I am guessing it will be Water/Dragon for its final evolution. I know some people are saying ghost but I don't think so since it when it becomes invisible it is because of camouflage, Ghosts aren't really invisible as they are more of things that phase through stuff. So I am thinking Water/Dragon or Water/poison.
Scorbunny is definitely the one I'll get!
He looks playful and energetic, which makes it that much more adorable IMHO.
Hoping that it will get Electric as a secondary typing upon evolution.
I don't know why I'm saying this, since I don't have any kind of proof.
It's just an hunch I guess.
Scorbunny caught my attention the fastest but I also love the other two. I really hope they have great Hidden Abilities, I can see Speed Boost on Scorbunny and maybe some kind of evasive ability on Sobble since it can camouflage itself (please don't have Wimp Out or Emergency Exit, lol), and for Grookey it's a little difficult to come up with an idea. I thought Harvest at first but I'd rather it didn't have that one.
I don't mind the secondary types I just hope that they're not pure. Gen 5 disappointed me by having 2 fully evolved sole typing starters so I hope they continue the recent trend of giving EVERY starter a dual typed final evolution.
My track record on first runs, as far back as I remember:
G4: I trained all 3 at once! (native file Turtwig)
G5: Oshawott, all day
G6: Chespin. Loved Fennekin at first, but then the evos were revealed. (Braixen didn't strike my fancy, but I still think XY had the best starters yet)
G7: Popplio (Primarina's girly too but not humanoid, and a strong endgame 'mon besides.)
And now we have a bunny who sets fire everywhere he goes.
I need it. I'm overdue for a first-time Fire starter.