Blizzard said it will choose players who have active subscriptions to the regular game based on a variety of factors to help them test the beta. It could be based on your PC, your commitment to the game, or just your luck. If you get in, you’ll likely receive an email, but if not, you can check your launcher. And remember: as with any beta, your progress will not be saved for when the game launches later this year.
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.