I didn't pick him, but Froakie is a pure blessing. it answers all of my problems with Water starters of the past. Not that I disliked any of them. I actually like them all quite well, it's just that they were all pretty tank-like. Sluggish but strong. I was just waiting for a change of pace.
And Greninja delivered @_____@
Phenomenal speed stat, a wide and stylish movepool befitting a ninja, great offensive stats in tandem, and PROTEAN. Great stuff. The only problem is that tongue scarf, but I can look past it xD
Delphox is very much to my liking as well for that matter. My favorite in fact. Very beautiful and sage-like, right down to the name. It really feels like a fully realized and grown up version of what Braixen was meant to be in it's design (A Mage). And another nice change of pace, being Fire/Psychic. I was fortunate enough for mine to be Hasty when I picked her too :3
Chespin's line, I haven't really gotten a chance to know, but I will train with the Chespin that I got from Shauna and give some thoughts down the road.
I think Delphox's Sugimori Art makes it look a lot better than its in game sprite. In game its like a fox version of Gothitelle, while its artwork makes it look more mobile and in-action.