Chespin 6.5
I like the playfulness it gives out, but the I dislike the huge head and tail tip color.
Quilladin 5
I like how it retains the basic form's main characteristics and changes them naturally and gradually enough to remain close to the same thing, yet very different looking. That nose is a huge problem for me, though.
Fennekin 4
Too huge head, I dislike the ear hair, it's gross. A generic design all around.
Braixen 2
Unnatural evolution progress, it looks too human, the stick is creative but stupid, the legs don't even seem like a part of its body.
Froakie 9
For something with such huge eyes and head, its proportions are very well balanced. Nice colors, good concept.
Frogadier 8
Relatively natural progression, not as much as Quilladin, though. Nice tone. Nothing creative about it, though. The look in its eyes is a bit too different from that of Froakie.
Needless to say, I'll choose Chespin.