Always top up a battery whenever possible. They don't like to sit around with a partial charge. A topped up battery will outlast one that is fully charged and discharged all the time, especially if it sits for any period of time while discharged. The only exception to this rule is the Lithium based batteries. They seem to like a partial charge for long term storage, but they also don't suffer from the same effects of sulfation on the electrodes, which is the problem for most batteries.
Except for the Automag in front, its usually the man behind the equipment that counts.