Who said “ flat freq response “ is the best?

Flat freq response for what and for whom? An anechoic chamber? A high end audio show room? Tom, Dick or Harry’s room. Every room is different. And for whose ears? give me a break!

A flat frequency response means all frequencies are reproduced at the same amplitude. Even if that was somehow possible to achieve in a listening room, that would remotely resemble what live music sounds like. I think a better use of this measurement in as far as comparing speakers is concerned, is how wide of the frequency spectrum the speaker drivers can cover and not if there are ripples within that response.

There are some other important technical parameters to consider. Dynamic range, sensitivity, response to square wave, distortion. Frequency response is probably fourth or fifth down the list.

Your missing something!!