Which recognized head type is potentially less common in conformation-focused breeding programs?

Answer

Deer Head

Breeders focused on maintaining the traditional standard will favor the Apple Head, potentially making the Deer Head variation, characterized by a narrower, wedge-shaped skull, less common in conformation-focused breeding programs.

Which recognized head type is potentially less common in conformation-focused breeding programs?
rareDogtypebreedChihuahua