I've seen a number of diapers with a wide crotch. All of these have at least 8" wide padding in the middle:
- carousel
- peekabu
- magnifico
- safari/inspire+
- cuddlz (single tape version)
these are just a tiny bit less, maybe 7.5" ? but still plenty wide!
- space/simple/paws
- bellisimo/teddy/bianco/classico
- little rascals
It's hard to judge the thickness of dry padding, because diapers "fluff up" when removed from their bag, and diapers that aren't compressed much for bagging (like safari/inspire) are always fluffed up
Generally you can go by capacity though. And as a general rule, wider crotch diapers have thicker padding. Safari/Inspire+ are an example of about as thick and wide as it gets.