I need to buy about 200K/yr Amazon gift cards starting next year, mostly likely on Amazon itself. I don't have any desire to try to maximize X multipliers by buying them n at a time at a supermarket.

Which card would be OK for giving me points on this? I have several Amex and a couple Chase.

Would a possible technique be just buying a test card on each account and seeing which post with points? I'm assuming both Amex and Chase have visibility into what was purchased from Amazon.

Thanks!