If you "never" would buy first class tickets, then I agree with the poster saying to get the SkyMiles Platinum card, or else just drop the cards completely if your purchases cover the regular MQDs.
To be frank, it sounds like your mind was already made up by the post; we will support your decision and still let you post here
I will also remind you that the regular Amex Platinum card no longer works with gift cards for the $200 "incidentals" so you might need to re-evaluate that card too.