What works best?
What are you trying to clean off ?
Usually the brake pads keep them clean.
Brake cleaner works great for normal dirt and anything greasy .
If there is some pad residue, try a can of Brake cleaner and the scotch-brite. Be generous with the brake cleaner. You might want a couple cans to do all 3 rotors to have enough to really spray them down. Its cheap...you can usually find it for a couple bucks a can.
Jim