Decisions Decisions Decisions!

I need to decide between the 3 images below for the book cover for Mr. Pitt & Lickety's Split...

First Image: The two characters have very prominent teeth and tongue features

 

Second Image has less prominent teeth and tongue features

Last image has no teeth and tongue features

 I am leaning toward the image with "no teeth and tongue" features. Of course my son likes the first image with the prominent features, LOL! Decisions, Decisions, Decisions...