As far as initial protection, Zaino can't be beat by the carnaubas you are comparing it to. Zaino does specifically contain UV blockers while providing months worth of protection on a daily driver. P21S and Souveran, to my knowledge, don't offer any UV protection and certainly don't offer months worth of protection. This leaves one very subjective quality to compare....shine, which is all about personal preference. Personally after using carnaubas for years, I do prefer the look of 100% optical clarity that Zaino gives. It's just a very bright, deep, and clear shine, IMHO and I like it. I have tested the clarity of Zaino against P21S and there was a difference in the clarity of the reflections. However, the P21S and Souveran offer a slightly deeper shine and shimmer due to the high percentage of oils. Frequent applications of either wax will give you a great look and decent protection. Personally if I were going to use either wax on a daily driver, I'd first layer a few coats of a synthetic, like Klasse, for protection, then use the carnauba as the final appearance coat. But, that's just me...
:wavey