Here are two graphs consist of test results from amp A and B. Consider that the black line representing the original frequency response curve and the colored line representing the amplified signal's frequency response curve, which graph do you think is better? A or B?
If your answer is either one of them, you'll be wrong. Taking the black line as baseline, both amplified signal are able to match the original signal in very linear fashion across the whole spectrum, thus both are equally good. What you want to pay attention to the graph is whether the signal is colored (bumped up or down) or not, not how flat or curve the line is.
Are you reading the right baseline?