Which bike carrier system?

Hello everyone, I’m addressing you because I ask myself the following question. Which chassis system (AHK or rear flap, roof racks are not an option) is the better or the most sensible one. It would be important for me to have safety and stability in case of quick evasive & braking maneuvers, assembly and loading of the carrier, accessibility and expected damage to the rear flap (e.g. rear flap lifts, hinges, etc.), cost differences. I would add an AHK to my VW Passat Va riant B6 might have to be retrofitted. Would I be very pleased about your experiences, tips and advice