I don't think there is a better carnuba wax than P21S. I've tried quite a few and found this one the easiest to apply and remove, the best shine, and the longest lasting. There was a wax comparison published by "Guru Reports" a couple of years back that rated it as the best conventional wax, and as good in some of their eyes as the Zaino stuff (that seems tough to apply). My opinion of Mequiar's is that they are ok, but don't last very long at all. Guru Reports had the same results.
I recommend their starter kit with the wax, pre-wax cleanser, and car wash. Get a few good quality micro fiber towels and use them exclusively. Also get a clay bar. Griot's Garage has a lot of wonderful stuff. Their clay bar, towels, and other things like Speed Shine are great, but they don't sell P21S. If you can't find it locally, try California Car Covers (www.calcarcover.com) or Bavarian Autosport (www.bavauto.com). The really good stuff ain't cheap, but you really do get what you pay for.