Besides the mamey-sapote variety collections already mentioned, Fairchild Tropical Gardens' fruit evaluation property by the Montgomery Botanical Center, has, or at least used to have, over a dozen selections made by "Maestro' Eduardo Marín of Oxkutzcab, Yucatán, México, which were brought to Florida by Gary Zill [I was along as translator, five trips, mid 1980's thru 1990's.].
In most cases we listened to Marín's descriptions, then bought his grafted plants and introduced them to Florida through the USDA quarantine procedures, and then they were grown for evaluation at Zill's and Fairchild and Puerto Rico.
Varieties that I remember with pleasure having eaten at Marín's house were 'Lorito' and 'Marin.' Both were top quality flavor, at least as good as 'Pantin.' Both had perfect texture and deep red pulp. "Marín' was longer than 'Pantin.' 'Lorito' was a smaller oval fruit, nice size for a couple of servings. "Lorito," which means "Parrot," was the nickname of the owner of the original seedling tree, because he rarely stopped talking!
Some of the varieties already mentioned in this thread were among these introductions, such as 'Alejo,' 'Cepeda Especial,' and 'Felipe Mayo.'
Another of that group of introductions, I forget the name, that I ate at Zill's, had purple pulp.