The iPhone 4S was far and away the most-activated device during the March quarter by Good Technology enterprise customers, a new study by the firm says. The phone represented 37 percent of activations, roughly four times the amount of any other device. The iPad 2 took home second place at 17.7 percent; the third-gen iPad came in fourth at 4.3 percent, but was only available for less than one month in the quarter, and nevertheless accounted for 12.1 percent of all of the March activations Good tracked.