Paste wax is harder to apply, but in my opinion it lasts longer. The liquid waxes - like Zymol - are MUCH easier to put on and take off, but I feel they lose just a bit of longevity in the process. A good paste wax should last 6 months while Zymol loses its luster after about 4. If you're after the best protection you can get from your wax, then you'll need to do the Zymol about 3 times a year. The harder paste waxes should be good for two applications a year. All of this is subjective. There are many who only wax once a year and then there are the nut cases who wax every other weekend.
Me? I'm in the 3 times a year crowd myself....
