Short vs Long Axis rooms: What type of speaker??

I have always thought that large floor standers, electrostatics, or planars sound best firing down the long axis. I have in the past tried short axis placement on a few speakers, and found the sound to be OK, but flat, and pancaked into a wide, but one dimensional soundstage with little to no notable depth.

However, my question is: do certain speaker designs and/or sizes provide better sound on either a short or long axis??, or, is the sound more determined by room acoustics than speaker/room placement interface??