From the NG FCTM:
Carbon Brake Life
For carbon brakes (as installed), brake wear is primarily dependent upon the number of brake applications. For example, one firm brake application causes less wear than several light applications. Continuous light applications of the brakes to keep the airplane from accelerating over a long period of time (riding the brakes) to maintain a constant taxi speed produces more wear than proper brake application.
During taxi, proper braking should involve applying brakes to decelerate the airplane, releasing the brakes when the lower speed is attained and allowing the airplane to accelerate, then repeating.
During landing, one hard, high energy, long-duration brake application produces the same amount of wear as a light, low-energy, short application. This is different from steel brakes that wear as a function of the energy input during the stop.
For normal landing conditions, autobrakes 2 or 3 optimizes brake wear, passenger comfort, and stopping performance. Since autobrake settings apply the brakes dependant upon the deceleration rate, an autobrake setting of 1 results in a higher probability that the autobrakes will modulate, especially when the reversers are used. Autobrakes 2 or 3 results in a continuous brake application, which can increase carbon brake life.
It all depends on what type of brakes you have. According to the quote above A/B1 seems a less than optimum choice IF you have carbon brakes. Having said that, I personally can't remember ever using A/B1 on landing.