“When I visited Cliff England last year the ones that were producing quite well were Sugarcane, Shanxi Li, Redlands, Dae Sol Jo, Bok Jo, and Xu Zhou…and I believe Honey Jar as well.”
I have HJ, Sugar Cane and Shanxi Li. All have produced fruited for 3 years. Shaxi Li is not productive at all in my yard. I think @BobVance has the same experience.
HJ and SC have produced well. It seems to me the two factors contributing to productivity is being in full sun and planting in close proximity for cross pollination. I do not know how much fertilization plays a role in jujubes being productive. @tonyOmahaz5 has good success with jujube production when he fertilizes them, in addition to having the two factors I mentioned.
I have started fertilizing my jujubes last year, 2018. Coincidentally, the production went noticeably up from 2017.