Wax is for tinkering around with show cars. If you want low cost and durability, get a sealant like Opti-seal.
Even though he asked "what wax", I feel inclined to say the exact same thing. The days of waxing a daily driver are long past, I think. Show cars are obviously a different story. I waxed my pop's '76 Imperial 1 year ago, but it's been outside twice since.
Reload or WetCoat are also good spray sealants that surpass wax in nearly every category.
Don't listen to these two coating snobs, millions of people still use and love wax. Every waxing thread always has a couple guys that just have to come in and tell you how great thier coatings are. Never fails