The cool, neutral one
The macho one
The feminine one

This could have even started back in Gen 5 with Serperior (feminine) Emboar (Macho) Samurott (Cool). Though Serperior isn't that feminine, and Samurott could also fit into the macho category.

They've gone with this approach as technically, everyone should have a favorite as they're appealing to 3 unique different tastes.

Through this, we can guess the next starters will be -

Fire (cool) - makes sense, as the fire type hasn't had a sleak design in a while, and the cool category is generally the most "shilled". With Greninja last gen, and supposedly Decidueye this gen, it makes sense fire gets it next.

If it's following the chinese zodiac system, I guess Snake could fit well into this role.

Water (macho) - Again, it's been a while since water had a beefy designed starter. There are a lot of animals they could go with, but my top guesses would be an elephant or a crab.

Grass (feminine) - again, after having a macho and cool one for the past gens, a more graceful design could be a nice change. A deer is a popular choice, and would fit well, but if gamefreak can turn an emo cat into a heel wrestler, they could change all sorts of animals to fit this role.

What are your opinions on the new style of starters? Do you think the design ethic is good and offers a diverse range, or do you miss the more animal like appearance of the older starters?

What animals do you think the next starters will be based on?