I've noticed that in for example 3x3, there are no best cubes, it's 100% Personal preference and no cube is better than any other cube.
But on say 2x2, the DaYan is the best. On 4x4, the AoSu or the Mini AoSu are the best. 5x5, YuXin. 6x6, AoShi. 7x7, Cubic AoFu GT, square-1, QiYi, best...