As in my own experience:
You will encounter both good mannered and very toxic people on this realm there is no mid-ground unfortunately and i strongly encourage to tab general and trade chat in a separate channel too keep your insanity and mood up.
Alliance are the dominant faction and you will find a lot of openworld at many places.
Even tho horde is the less dominant the role playing exist! But very guild oriented, you will find openworld roleplay in small places such as Valley of Honor in Ogrimmar and Crossroad at Northern Barrens.
I would suggest too look up this community Known as PCU were a lot of like minded guilds makes events an all the fun bits.
Hopefully one of these guilds will be a suitable home for you here and hopefully wont feel a regret too give argent dawn a try. 