I use either Break Free CLP or Hoppes. Pretty standard. I'll pick up other varieties of extra strength bore cleaners now and then for some heavy duty stuff considering I don't have a dry solvent tank available.
Like most, I've tried many. Right now, I use Butch's Bore Shine for for powder residue, and Montana Extreme Copper Killer for copper. The Montana is the absolute best I've used for copper; usually don't need a brush, just patches until it comes clean. When I do use a brush, its nylon.
Bought a used rifle a couple of months ago; nastiest bore I've seen. I resorted to JB's bore paste to get most of the fouling out, then finished with the combination above.