maybe neither!
I apply a QD(quick detail) mist-like Zaino Z6, to the car immediately after driving it to remove any tar, bugs, etc. before they harden and force me to use something stronger on them.

, as well as clean the wheels with a damp towel. this also enhances the Zaino finish. Removing the contaminants while they are fresh also means that I won't be scratching the surface-the QD pulls them right off.
Then, before I drive it, i run a CA duster over the entire car.
When I return, same thing again.
this way I wash the car as little as possible which translates into fewer fine scratches and swirls over time. washing actually causes wax breakdown faster than anything else, i have found after many years of detailing-it's a passion of mine.
Obviously if the car gets really dusty or rained on while driving, there is no choice but to wash it when I return.....