I do have an AirFrance KLM Amex gold. It gives me 1 statut mile per €, or 1.4 statut miles per € with AirFrance and Hertz.
It's not outstanding since you have to spend 20k € to win a domestic/europe return ticket.
That said, the AMEX comes with pretty good insurance (ski, travel, lost lugguages, delays, ...) It could also help to achive an Elite Statut with Skyteam.
I'm happy with this card and try to use it as soon as possible. Unfortunatelly, AMEX is not very popular in France, due to a big commision rate in comparaison with VISA and MasterCard. So I also have a VISA Premier to buy ... some food for example
I do recommend it: you have a bonus miles at sign up (I think it's 3000). If you are a FF
, it's also a good way to pack extra miles.
It costs me 110€ per year witch is on average the price for the VISA Premier.