So there is something in Legion that bothers me and think it is bad design choice from Blizzard. The thing is to unlock the much advertised world quests you have to reach friendly with all 5 factions of legion. Each of these 5 factions are in one of the 5 zones, so 1 faction per zone.
The thing is if you do everything in a zone, from what I have heard, you need 2-2.5 zones to reach 110 level but that will leave you with 1-2 zones you haven't been into (lets exclude suramar) and have no reputation from the faction in that zone. So the suggested path in order to unlock the world quests is to only do the main quests in the zones and ignore the side quests so you visit as many zones as possible before you reach level 110.
I find that really bad design for people who like to 100% a zone before they move on, because they will unlock the world quests much later. Maybe everything I say is wrong and someone who leveled fully in the beta can confirm if getting friendly with all the factions is a piss easy thing to do. I had beta but didn't leveled because I didn't want to spoil things, so maybe I am wrong.