I've used "tank ring" bags and kinda like 'em but find that the bag release mechanism tends to be troublesome most of the time. Perhaps I'm impatient but I've found that a magnetic mount bag tends to work best for me.
Soon after I acquired my ST3 I took it to a local auto specialist/body wrap shop and had them wrap the tank and fairing with a 3M film. I then bought a Cortech expandable bag that holds quite a bit of stuff in its standard for and a lot of stuff when you unzip the base layer to expand its capacity. Under the Cortech bag I placed a microfiber clothe to provide a buffer between the bag's magnets and the film. It easily slides out of the way when accessing the fuel filler cap and has a very clean appearance.
