It can be argued that synthetic sealants give a brighter shine than carnauba does, but that carnauba gives a deeper and wetter look than synthetics do. Those who complain about the look of Zaino often say it makes a car look like it's wrapped in plastic. What I find is that synthetics do a great job on lighter colors, especially silver and white, since those colors can't really show depth like black, red, and other dark colors do. Carnauba waxes tend to enhance that depth in darker colors.

Having said that I've seen side by side tests with NXT 2.0 on black cars where it actually made the black look blacker, darker and richer than the untreated "control" area.

My personal preferences: M21 Synthetic Sealant 2.0 topped with either M26 Hi-Tech Yellow Wax or M16 Professional Paste Wax (although M16 was discontinued two years ago). The key word here is "preference". Your car, your money, your expectations. Find something you like and use it often.