I long ago learned that I prefer music reproduced by drivers having large radiating surfaces (ESL’s, magnetic-planars) rather than comparatively-small direct radiators (domes, 3"-5" cones), and that I prefer line-sources to point-sources. Small drivers/point-sources make music appear to be coming through two bricks (one for each channel) removed from a wall separating myself from the performers.
I also like voices to appear to be coming from the height of the mouth of a standing person, rather than at knee or even waist height. I like the performers to be above ear-level, as if on a raised stage, rather than looking down at them from a balcony. Also, small loudspeakers miniaturize the sound of a grand piano, drumset, upright bass, etc., turning a life-size house into a dollhouse.
What I haven’t heard is a large loudspeaker that is a line array of small drivers, like those designed by Danny Richie of GR Research (and others, of course).
So, whether mono or stereo, size matters to me. And though mono recordings can sound smaller in the left-to-right plane, they can still possess great depth.