AXA WiseGuard Medical Insurance Plan is the insurer's Standard VHIS plan (the regulatory floor of cover), while AXA WiseGuard Pro Medical Insurance Plan - Regular is its flagship Flexi plan, which extends the ward class, benefit limits and geographical coverage above that floor.
AXA WiseGuard Medical Insurance Plan suits you better if you value a lower entry premium (about HK$2,852/yr at age 40, non-smoker). AXA WiseGuard Pro Medical Insurance Plan - Regular suits you better if you value a higher annual benefit limit (HK$5,000,000).
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.