Nothing unique about my needs outside of my personal expectations and preference for metal over plastic for the mount system. Sure wish I could see the Arkel bags in person, but from what I can see online, the mount system is superior. The Jandd bags I just picked up easily mount up and are super secure. The bags are going nowhere, don't move around and don't need shims. Again, a superior design.
Keep in mind each individual has their own peculiarities, and mine are lifetime durability and simplicity. FWIW, my car is an 88 Volvo 240, which may help explain things.