They each have an advantage in different situations. The rear blade works by moving material back and forth across the road and is good for pulling material from the sides and moving it towards the center to fill ruts or build a crown. The rear blade is the universal road tool. The box blade works by moving material along the road and will fill pot holes and smooth up the road but it is more difficult to contour the road with the box blade although it can be done. The scarifiers on the box blade are very helpful in losening up a hard packed surface. The rear blade will fix wash board easier because the blade is angled across them obliquely where the box blade will tend to follow the crests and valleys.
What ever you get you will want it to be as heavy as possible so that it will cut properly. A box blade should be about as wide or slightly wider than your rear tires and the rear blade should be about a foot wider so that when it is angled it will be a little wider than the tires. You want to maximize the weight per foot of blade. One hundred pounds per foot or more is a good target for working on hard packed roads. If the blade isnt that heavy try adding weight to it.
Every driveway is different. Depending on material makeup, weather, and traffic. On mine the rear blade is what I used most until I got a scraper grader. I still use the rear blade but not as much. You should look at scraper graders.
This is all just my opinion and you will find others have a different opinion.