To expand a little.
As expidite said the autobrake setting is a deceleration rate, if full reverse is selected it will make no difference to the stopping distance, as the brakes will simply release a bit, to maintain the same rate of deceleration. ATC expect you to take the first available taxiway given your aircraft type, which will usually require autobrakes 2 or 3. When this is the case we use full reverse, as it saves the brakes from becoming too hot (although with new carbon fibre brakes this may not actually reduce brake wear). If we're ever given a roll-through, or dont have to take the first available taxiway, then autobrakes 1 is selected and idle reverse used. It depends on the situation, and will largely be based on your previous experience at that airport.
The only other consideration is if you're operating off a wet/slippery runway, in this situation you cannot be assured the wheels will grip well, making the wheel brakes useless, you MUST use full reverse in this situation. (this all applies to 767 ops).
The definition of idle reverse is simply deploy the reversers (engine cowl slides back, blocker doors direct airflow forward not back) without increasing the engine power above idle.