Horde AH listings are more packed and also more liquid - meaning generally lower and more competitive prices but listings actually sell. This is true for both leveling gear and end-game gear. Alliance economy is generally very sparse, partly owing to max level Alliance players wasting A LOT of time PVPing lowbies, which is time not spent in dungeons, farming mats, etc that are productive for their economy.
Class diversity on Alliance is abysmal. Most Alliance players roll Paladin or DK. This makes Warrior - a class already notoriously difficult to gear in this patch - infinitely harder to gear on Alliance.
RE: WG, ever since Alliance got reported for exploiting/cheesing (camping Horde spawn when Horde controls fort), Alliance has really fallen behind on capping WG. On Europe hours, it's coin flip on whether Horde/Alliance controls WG. When the Americas are awake, it's almost always Horde.
There are toxic players on both sides. Anyone claiming one side is more toxic than the other is only opining based on anecdotal evidence.