"Best" one step is a bit of a tricky issue.... it's like trying to ask someone what the "best" polish is.
Do you want better looks? More cleaning? Greater longevity? Ease of use?
:nixweiss
Something Autopian pros or semi-pros like to use (like Meguiar's #66 ) is going to be different from what you might give to your friends or relatives to use on their cars....