It looks like you're having trouble deciding, off and on, more or less. Each puppet is what you make it. I would definitely go with a Diva over Rodney because a Diva appeals to all ages (except 3rd and 4th grade boys who don't like girls). You can also put some gorgeous outfits on a Diva at different times of the year to fit a Christmas show, summer, etc. If you use a female voice it is easy to distinguish from your own (I am assuming here).
However, I still think that Willie the Kid is an amazing creation and extremely versatile. If you are a taller person I believe he is larger than a Diva and would blend with you better. Down through the ages the typical vent partner has been a boy, probably because it's easier to get comedy from a boy puppet. But the best way to decide is to show the pictures to some kids. They know what they like and they will probably be your biggest audience.