A UK-based electronics testing and recommendation magazine and website, Which, has rated the tablet battery life of various sized tablets -- and found that the iPad and iPad mini ran away with the competition, besting its rivals by very significant scores. While scores were closer between the iPad 2 and the better 10-inch tablets, the Retina fourth-gen iPad model's score was well over 50 percent better than the combined average of the competitor tablets, with all screens set at equal brightness.