Im in 9b near the east coast of central Florida
Mango but it takes a lot of work to keep it alive and fruiting, a late winter blast like last year can destroy blooms.
As far as easy, mulberry.
Who the heck thinks citrus is easy in Florida? It takes more fertilizer, leaf sprays, and pesticide to keep them even remotely healthy than any other tree family with everything out there trying to kill them.