natural bristle back scrubber - the kind that you can remove the long handle from and has a strap on the back for in-hand use.
I *hate* the plastic squishy things, something about the texture and how the plastic net rubs together when you hold it creeps me out.
loofahs tend to lose their texture fairly quickly.
washcloths get mildewy and stink.
hands work too.
and generally shampoo, not soap. soap makes my skin prickle when I dry off.
I know, I know, all kinds of little weird here. but hey, it's MY bath.