I'll play:
PADI: still here, still big. Do you want fries with that?
SSI: No, we're not a PADI shop. Yes, we do dive courses.
RAID: Not just rebreathers, promise. Did you know we don't print books?
ACUC: Canadian eh? Sorry for the ice in your OW checkout dives.
NAUI: We might only have 50 instructors, but they've got 50 years experience each.
BSAC: Recreational depth, what's that?
NACD: Vote pizza!
In short, I can make up caricatures of the agencies I've encountered in 2018, but at the end of the day... Dive instruction is about people, not a product.
I've met wonderful and horrible instructors in every agency (many teach for multiple agencies) and my sample size is too small to make useful comparisons globally.
Cameron