Chubb VHIS - Superb Plan and HSBC Voluntary Health Insurance Flexi Plan - Bronze level are both High-end VHIS plans; they differ in ward class, benefit limits, geographical coverage and premium.
Chubb VHIS - Superb Plan suits you better if you value a higher annual benefit limit (HK$6,000,000). HSBC Voluntary Health Insurance Flexi Plan - Bronze level suits you better if you value a stated lifetime benefit cap (HK$20,000,000) and a lower entry premium (about HK$10,926/yr at age 40, non-smoker).
Neither plan is categorically better — your choice should rest on your own budget, where you expect to seek treatment and your family needs, ideally after a financial needs analysis.