The bigger enclosure of a floorstander doesn't always equal bigger sound. More control is needed in a larger enclosure. The Quad 12L2s or Quad 11L2s standmounts being a case in point as compared to the Quad 21Ls. Almost the same speaker, but in different enclosures. The standmounts sound large and full, and their size is deceptive. Standmounts seem to allow for easier positioning, since they're lighter, and with the correct stands appear to take less space. Also easier to move around. One minor plus for the floorstanders are that the cables are easily concealed, but of course you could tidy cables with standmounts.
This is all at the lower (3k +) budget. When going higher end, the floorstander may win out, allowing for extra woofers, etc. the scale is better. Just my experience so far