I haven't heard the box speakers others have mentioned.
I have long been a fan of panel speakers, however. I owned Magneplanar 3.xs and upgraded to the Apogee Duetta IIs that I still use. A consideration that none have mentioned is soundstage height. A tall speaker like a planar magnetic or electrostat can convey (artificially) soundstage height. For example, the high frequencies of the cymbals of a drum kit will be at a realistic height, while the bass drum will come from lower in the speaker. You could get this with a bookshelf speaker on a tall stand, coupled with subwoofers. I suspect that panel speakers can more easily throw a deep soundstage, however.
I think the less-pinpoint imaging of panel speakers is more like live music than the imaging of conventional drivers.
I would suggest you do your listening tests with well-recorded orchestral music, preferably recordings like the 2 or 3 microphone recordings done in the late 1950s or more recently by labels such as Telarc. This will reveal authentic soundstaging as well as natural timbre better than electronic music genres. You could include those other genres for judging other sonic aspects, though.
After listening at showrooms, if you can get speakers that you can return if they don't work in your room, that would be helpful. That's one of the best reasons to buy new--a dealer is more likely to allow that than someone selling their used speakers, but I guess you never know.