Vodafone: available many countries in Western Europe, though they still charge roaming fees when going to another country
Telcel seems like a monopoly but that's the easiest one to find and there's an actual office in the airport
Power 3G is available at the arrival lounge but quite pricey at ~$30USD...
I can't recall what the brand is. I just see the "M" logo in my pocket.
Optus - quite cheap at about $2 AUD a day for data but be prepared for long lines at the airport. Alternatives are pricey $40+.
Spark - available at the airport. Cheapest is $19 but that only comes with 500 GB, go with the higher plan if you're using your phone for GPS. Reloadable at dairy stores!
Sun - great for unlimited domestic calls and texts but 4G connectivity is dismal
Globe & Smart - 4G connectivity is not great, but usable