I had the white case for my white s4. Felt that it was too plain so I got the red one and I love it. It gives it the nice pop and looks great with the white phone. To the guy above: your pictures convinced me to get the red.
I got the Metal Slate version of the slim armor, and I was pleasantly surprised by the color. It's blue, but more like a graphite blue. That might look good.
I got that the metal slate for my black S4 and I absolutely love it!!! Just ordered my wife the Dante red case. I think that any of the color combinations would look good on the white case.