A good one piece cleaning rod like Dewey, Tipton, Pro Shot etc, used with a proper bore guide.
+99999999 on that. they are great. just enough flex, smooth rod, great bearings, i wouldnt change a thing. if you have something like a 10/22 and it doesnt have a cleaning hole in the back you are better off with a boresnake though. for bolt action and any action you can put a rod down the back of you wont regret the tipton rods.I always use the Tipton Carbon Fibre ones.
I picked up an old copy of a gunsmithing book, and the author recommended steel rods. Not sure if I agree, but his logic was that softer materials (aluminum, brass) could pick up and retain grit and retain it , which could scratch the bore, whereas steel rods were easier to clean and would not retain any grit to harm the bore. Plus they are stronger.
Avoid the cheap aluminum rods, they don't last very long and bend and break easily.