I don't know of any manzanita that has been actually selected for fruit quality, since they are used as ornamentals. Sort of like trying to find a mesquite tree with the best tasting beans...
If you can find some specimens that have fruit on them at a nursery, I would just sample them until you find a species you like. I am partial to kinnickinnik myself, but they are a groundcover, not a bush/tree.
Good luck! Maybe YOU can selectively breed for fruit, then market it! Of course, it may take a few decades...
Cheers,
Carolyn
