The flat Scothcbrite pads.
I use the 2" and 3" flat pads that go on the 1/4 turn mandrels. I prefer them over the large barrel type, which don't always behave on a high speed grinder. The Red colored pads are the best all around "grit" and the Blues will get things a little smoother. There are many different Scothbrite products, and I have most of them in my arsenal, however the flat discs will do nearly everything. I have been using them for 40 years, and I have tried a handful of other products, but always come back the flat disc.