To me accurate connotes measurement. As has been discussed quite a lot by enthusiasts and designers is that perfect flat speakers generally sound bad, sterile, unnatural. Planners tend to be very fast and are capable of reproducing sound well above the range of hearing, which through interaction of harmonics impact sound in the range of hearing creating a bit of magic… commanding one’s attention. I owned some form of planar… and extensively auditioned large Maggie’s and others a lot over fifty years. I switched over to dynamic about twelve years ago and my system started moving much closer to reproducing the nuances live acoustic music. But I also changed an upgraded all of my electronics so, I am not arguing that dynamic hold the top position.
With excellent no holes barred setups large planar, horn, as well as dynamic speakers can reproduce music that is nothing less than miraculous… showing little weakness in speed, tonal balance… etc. The strengths and weaknesses of each category tend to come out in less than ideal (by ideal… I mean great rooms and many $100K, top notch speakers an equipment supporting them), like in the systems most of us own.
If you only are interested in the academic question of frequency response, then I am sure someone will jump in with an answer.