I would not call Pantins small. They may not be as big as Magana but their size isn't too shabby.
Despite what Alexi says, Magana is not in the same class as Pantin, Lorito and Pace when it comes to flavor and texture. There is also something to be said about grocery store bought mameys...no comparison to home grown and properly picked (as with all grocery store fruit when compared to home grown and harvested).
Viejo is a smaller mango and flavor and texture are inconsistent from the ones I have had.
I personally like Lorito the best but Pantin is excellent also. Another excellent but lesser known variety is Excalibur. It is totally different in shape, longer and not as fat with a pointed end, and the flesh is super sweet with the darkest red color of any variety that i have seen.
As Noel said, i am very excited to see the new cultivar(s) mentioned by Richard Campbell.