I know what you mean, but how about this? I've used ClearKote's QS to clean relatively dirty cars without causing any marring (black BMW in direct sunlight). It was a bit scary at first, but after watching that video someone here posted, I just had to give it a shot. It worked like a dream. This experience has piqued my interest in PB's S&W.
Oh, and back to the original topic, my favorites are Z-6, QS & OGSO. Out of these three, I give the slight edge to Z-6....but like the previous posters have hinted....a lot of it will depend on the situation you're using it for.
No wax in any of the Meguiar's QD products. The Quick Wax has been reformulated and has some amazing results for improving depth and shine. There is a review thread about it if you want more information you can do a search.