HUGE fan of the Bags Connection tank-bag system - had the adapter plate on three separate bikes and couple of difference size bags that I could permutate as the requirement dictated
Nice small one for about town stuff and bigger one for trips.
Is an absolute dream at gas stops - seconds off and on.
I don't even use the 'safety' strap that goes around head-stock - just unnecessary IMO
(I have the slightly older system but principle essentially the same)
I'm actually thinking about getting an extra set of adapters (both parts) and fitting to a a spare tail seat I have, and mounting rear bag that way also.