Biz Plat has the best credits that reset every calendar year. But you can do it with other Amexes.
Australian Amex cards aren't churnable like US Amex cards are, so not worth it.
You can sign up for a new Biz Plat every 90 days. But always good to time the one you sign up for in the fourth quarter to make use of the triple dip.
So are the USA Amex Biz cards different from Amex personal cards in that you still get a sign up bonus every 90 days instead of the 7 years?