Speakers that excel at depth/layering/space

I don't think it's JUST speakers that determine this. It is the interface between all of the components that will ultimately determine how well the system images. IOW changes in the front end could potentially have an effect. The interface between speakers and amp could have an effect. Etc.

That said, I've found simpler designs with minimal or no crossover...single driver, and monitors, for instance, both excel at soundstaging depth. SET amps paired up with the right speakers are world-class at creating a holographic stage, but they don't serve as wide a variety of program material as well. OTL also do quite good paired up with the right speakers and are more versatile than SET. But it's not just the speakers.

As an addendum to my post above, probably one of the best imaging systems I've ever heard contradicts pretty much everything I said there, so go figure. I'd still stand by those observations. The best I've heard was an all MBL system set up in a very large space at one of the shows (RMAF or CES, can't recall which). I'd heard it since not sounding this good so they must've just hit it right with the room and the synergy, but it left me speechless. It had the holography and natural presence of a SET system with the drive, dynamics and energy of the very best SS (it was entirely SS). Not sure which models, but it was basically their all-out-assault system at the time. It was the same system, or very close to it, that didn't move me nearly as much in a different room at a different show, going to show you that it's not just one aspect of any system (in this case I think it was the room that really was the make or break factor, but who knows).