Usually the referral bonus is only 15,000 MR and you can only refer friends for the 40,000
MR sign up offer which doesn't make sense.
On the surface the original American Express platinum looks one of the weakest (Goldman Sachs card is by far the worst option) but you need to remember that people often receive
sign up bonuses of 100,000 / 150,000
MR points (the best way to check for these
offers is with the American Express pre-approval tool).