Often the name modification (or "mod" for short) is used interchangeably with AddOn. More specifically, a mod is a third-party AddOn that alters or enhances some aspect of the game's interface. Mods can perform a wide variety of tasks, including adding new buttons to the screen, altering the built-in player and party frames. In extreme cases, mods completely supplant the standard game's interface, usually offering more advanced functionality.
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.
If you want to get rid of all of registries left on the program removal and don't want your Windows system is fill with redundant registries that someday may affect the system performance, you should perform a registry scan and clean with a sophisticated registry optimizer, it will help you clean all the useless and corrupted registry files on the system.
The best part about the guides, though, is that you won't be sidetracked by various other quests. For example, if you're a dwarf questing through Eastern Kingdoms & get that random quest that takes you to Feralas, Zygor will keep you on track by putting that Feralas quest on the back burner while you keep chugging through the main storyline in Eastern Kingdoms.
The next biggest problem (after time) is deciding the format it should take. It seems to me, these quests will mostly be done while running around doing world quests. Since we can't predict what order someone will have world quests show up in, it is impossible to decide what order to put the quests in. Should it be one guide for all of Horde Kul Tiras and one for Alliance Zandalar, or one for each zone?
Now he's closing his project yet again. Leaving us all in the dark. Thanks to the few that have to "big men" in the torrent scene. I just hope that someone else comes along that knows what Whoknowsit does and is willing to put up with the egos and the BS in the scene to share the guides we all enjoy. Because all I've seen so far are a bunch of people stealing Whoknowsit's research and the donators' wishes to keep it in THIS scene and safe for THIS SCENE, who don't know what they are doing.