There’s something to be said for the aesthetics of the various character models Horde vs Alliance as they pertain to transmog. I would love some stats on Horde vs Ally, rates of transmog. I think gear is more discernible on Humans, Night Elves and Draenei than Blood Elves, etc. coincidentally my Ally-side endeavors have fared significantly better than those Horde-side.
Some smoke but could be some fire there - Ally players being more visually-conscious, concerned for looks, and the visual features of some of the Ally races lying closer to what is promoted in today’s media as being “beautiful” - and thus this desire from those players is naturally gravitating them to the appearance-driven feature of transmog. Would be curious to know how well others are selling, Horde vs Ally. Net-net, Ally side might be running to the AH faster than Horde during this initial wave, unless your realm is overrun with appearance-conscious Blood Elves.