I’mnnot sure I’ll be of much help, I have a tailfin system. I have to say, I really love their rack top bag as it’s very convenient and well made.
I tend to favour a durable and convenient system (usually unfortunately on the expensive side). When I’m not sure what features exactly I’m looking for Intend to buy the very cheapest option, and whilst using it work out what features are important to me. Then I buy the good stuff and give away/resell the cheaper system.
I think relatively low mounting option for panniers could be important, lower centre of gravity is important for ride quality/comfort. Also, important for you to be able to get the panniers sufficiently to the back so your heel doesn’t clip the bag. Stuff like a good light fixing spot is a nice-to-have - at least I always turn the lights on when it rains, for safety.
If my bike had the mounting points I would have gone for something nice from tubus or a similar manufactorer, but since it doesnt I had to pay 300 euros more for a tailfin (which, as a product, is really great by the way. But prohibitively expensive)
And I thought that 120€ for Tubus racks was a lot. I never considered the tailfin because I have lot of mount points.
I had borrowed bags that clipped my heels so in this case I know what to look for. I was just interested in some more options/ products that are good and i should consider.