Hi,

I am wondering if anyone has flown both and can compare? I have not flown either before.

I am flying from EZE - SFO overnight and the AeroMexico flight is ~$800 cheaper. From the pics and some reviews I've read the AeroMexico seat looks pretty good and am wondering if it's worth the extra to stick to United. Any other considerations to keep in mind besides the seat? I read somewhere that United doesn't always offer a mattress pad while AM does. For an overnight flight that seems like might make a difference in getting a good night's sleep?
For reference, I regularly fly the Qatar Qsuites so that is my (relatively high) benchmark

United Polaris : 777-200
AeroMexico PremierOne : 787-9 Collins Aerospace Super Diamond seat

Thanks!