I've amassed a huge collection of 5" ROS discs from buying into the specials. None of it is what I consider good stuff. For a long time I was sold on the Festool "Granat", last a long time.
Then
this video made me switch to the 3M "Xtract" and "Cubitron" discs.
Awesome products. The Cubitron is my favorite as the discs are more "rugged" but the Xtract does better with the dust collection. I really need to get a buffer pad for my sander which would help with the DC on the Cubitron.
Always blow the dust off of the pad and the back of the disc before installing as either of these have minimal "fuzz" to get a grip with the hooks on the pad.