Hi John,
I don't have the experience with all the different varieties to make a good recommendation. I didn't even know about all the new Zill mangoes until a couple years ago when I saw a Jace Mace and Shaymus video talking about them. I found this forum when I was trying to find more information.
I selected Glenn and Nam Doc Mai originally from the information on the Pine Island Nursery website. Because of my cool climate, I chose Glenn because they stated it was the best early season and Nam Doc Mai because it could be eaten at the green stage.
I find it interesting that the experience of most in SoCal has been negative with Florida grafted trees and that the most recommended is Manilla for rootstock. When I first planted my trees, I also planted several Champagne and Keitt seeds because those fruits were available locally. The Champagne/ Ataulfo seedlings are not vigorous at all for me, maybe they need more heat. I have one Keitt seedling that is about 13 years old but it is still pretty small and gets powdery mildew consistently despite being in a sunnier location. I'm guessing Keitt needs more heat as well since they're growing it commercially in the desert. I've grafted it so we'll see how it does.
My home garden soil is alkaline, heavy clay. I have some thoughts about why my Florida trees have done okay for me, but maybe that's too much to get into now.
Janet