I usually like grass types best but Chespin is just ew. So I'd probably go with Froakie because, even though Fennekin is cute, fire Pokemon aren't my thing.
I normally always go for Grass type, but I think this time I'll go with the cute little frog, and dedicate it to my first Umi no Tamagotchi: KeroPyontchi
I was going to choose Froakie on my game... until it was revealed that the Kanto starters are in and obtainable. Considering my first Pokemon was a Squirtle back in the Red and Blue days, I'm going with Fennekin to balance things out for when I get Squirtle again.
I'd actually chose Chespin, I'm not sure why but I just like him more than the others. Also, I'm getting Bulbasaur because NO ONE EVER PICKS HIM. So Grass-type all the way for me!
Chespin. I have a feeling he'll be Grass/Ground or Grass/Rock but most likely Grass/Ground. He looks cute ^_^ Plus I'd be getting Squirlte ( IF I HAD A 3DS D: ) because there's a free Torchic so I can have 3 different types. Weee~
Remember, chespin is the bulky starter. So obviously it will be quite big. Just think of it as your awkward teenage years and then *BAM* an awesome bulky wall that can withstand hits.