I use Zaino and like it a lot. There are carnauba products that some will say have a deeper shinier gloss but there is no way it will protect the finish as long as Zaino. The bottom line is it is all about personal preference for your car. A good carnauba will protect your car finish as well as Zaino but it will only last 2 months at best. Zaino will last 8 months. Also in the hot weather carnuba wax products will actually melt and you will need to reapply the product. This usually only happens in the hottest southern states.
If you want to learn a little about protecting your cars finish cruise this board for a few weeks. http://bimmer.roadfly.org/bmw/forums/detailing/
Good luck with whatever system you choose to protect your car’* finish. Any protection is better than none at all.