We flow this route last week in First.

You'll only ever have New First to MEX. The outbound flight had fantastic food and a fairly terrible crew; the return had middling food and a phenomenal crew. It's quite a long outbound flight (c.11hr) so First is very welcome.

If you're transferring to an internal Aeromexico flight be aware that you'll need to transit from MEX Terminal 1 to Terminal 2 which is a bit of a pain and takes an hour or two if you're connecting directly. Enjoy!