Okay, I've finally updated the top ten, so far, with English titles when appropriate. DVD info to come. Lamentably, there's a lot of misinformation available online so one has to be careful (for instance, the directorial credits for El compadre Mendoza). But I've let the release years, which just may be the completion years you prefer, stand as they are.
Here's my meager Mexican Cinema Classics thread, though one with reviews of two of the top four on the list. More reviews to come, especially of those films that belong to the "Golden Age."
I'm sure you, and most others, are well familiar with the three Buñuels, so let me make a special mention for Ripstein's masterpiece, El lugar sin límites / The Place Without Limits, a film maudit of sorts which rips into the culture of machismo often celebrated in Mexican cinema. Frankly, you can do worse than tracking down any Ripstein film you can. Unless there's a Mexican Naruse who's yet to be discovered, he just may be the best filmmaker the country has produced so far. And he's only 64. Some notes in the Ripstein thread.