1, Tonality - Frequency response of the speaker in your room.
2. Accuracy - Frequency response of the speaker on its own.
3. Dynamics (Attack and Decay) - Can it play loud with low distortion?
4. Imaging - Good dispersion plus #2 and not screwing it up with your room.
5 Resolution - Low distortion and not screwing it up with your room.
6. Matched - Make sure it has enough power to get the volume levels you desire.
A flat response for a speaker is always wrong. Especially in the bass. Not only does no one make a speaker like that,
What the heck? Many make speakers with flat responses on their own, or try. That is not the same as the response of the speaker once it is in a room and because the response in the room is not the same as the speaker on its own does not mean it is not important. Are you sure you are meaning what you mean?