Looking for some advice on the standard non-branded Amex cards.

I'm a french resident and am planning multiple trips with Emirates so would like to earn as many Emirates Skywards miles as possible. I've come across an offer for the gold card which gives 80 euros cashback at 400 spend. The green card has a 15000 MR welcome offer which seems more interesting to me. Both free in the first year. So now I'm thinking of getting the green card as my main priority is earning miles.

My question is whether I am missing something by not getting the gold card? Do Amex do offers during the year that apply to the gold card but not the green card? Insurance wise I'm good with my Visa Platinum.

Called AMEX this morning to see whether it was possible to have an MR welcome bonus instead of the 80 euros cashback for the gold card but this was met with a firm no.

Doing the maths, at a 5:4 ratio, 15000 MR can be converted to 12000 skywards miles. Purchasing 12000 skywards miles directly with Emirates would cost at least $240 (1000 miles is $20 at the moment) so better than 80 euros cashback.

Thoughts on this? Also, are there any other cards in France that I'd be better off getting?