War Mode: War Mode can be turned on at level 30 through your talent window, and will give you 10% bonus XP. You will, however, be attackable by players of the opposing faction, but changes have been made so that all players have a fair shot in a fight and even low-level players can kill much higher level players, and at least not get ganked and one shotted. Note: As of patch 8.1, you can get an additional call to arms bonus with war mode on if your faction is underepresented.
I used Zygor for legion and BFA, used AA on an alt for BFA. Personally i like Zygors format more. I like being able to target things like achievements. I used Zygor to get my Mindworm and my Lucid Nightmare as well as finish the Rep grinds for the allied races. I have zero complaints. My experience was great. I also used Zygor for some professions, recipe acquisition, a couple mounts, all of the Suramar quest line. Thank God for that. And for the last zone of Draenor on my Demon Hunter.. i forget the name.. Whatever the big daily hub thing was called.