This is a toughy, folks. You may think you know your answer--know yourself. But when you give it more than a fleeting thought (which, let's be honest, is all the thought this question really deserves, but humor me), you may surprise yourself with how little you know the person within your skin. SOMEONE PLAY SOME DRAMATIC MUSIC.
My knee-jerk response: I prefer bar soap. I have always loved bar soap. The beautiful packaging some of it comes in makes it feel like a present, and the solidity in your hand once you unwrap it feels like talisman or something. If I were in Inception, a bar of soap would be my totem.
But then the disappointment sets in as I start to use it, not because it doesn't get me clean enough, but because as soon as it starts shrinking, losing form, becoming malleable... I lose interest. I'm like one of those creepy guys that wants to have sex only with virgins. But soap.
Body wash, on the other hand, may not have the prettiest presentation or offer an indescribably magical heft when you hold it, but it never really lets you down. You can apply it with your hands or with a poof; if you spill some, you don't have to pick it up; and the bottle doesn't go through a sad Dark Crystal Podling morph as you use it.
Y'all, I don't think I can answer my own Quick Question today. But you can try: Body wash or bar soap?