I've read somewhere that Jazz basses are a lot more popular.
Both are arguably popular but I'd say for kids starting out or guitarists turned bassists, I would agree that the J is popular amongst those groups. Just to name a few.
If you're in the rock, punk, or heavier music genres, most would go for the P.
Then again, not everyone is a bass geek like us. They just buy what sounds nice and feels comfortable to then