Dugi’s leveling guide is the leveling addon I’ve always used to level as fast as possible. It will show you where to go and what to do in-game, speeding up the leveling process. This is optional though, as the game already does a pretty good job at showing you where to go at all times. The addon does, however, come with a couple of other nice features and perks.
Alpha Beta PTR Classic 1.1.0 1.2.0 1.3.0 1.4.0 1.5.0 1.6.0 1.6.1 1.7.0 1.8.0 1.8.4 1.9.0 1.10.0 1.11.0 1.12.0 Burning Crusade 2.0.1 2.0.3 2.0.4 2.1.0 2.1.2 2.2.0 2.3.0 2.4.0 2.4.3 Wrath of the Lich King 3.0.2 3.0.3 3.0.8 3.1.0 3.2.0 3.2.2 3.3.0 3.3.3 Cataclysm 4.0.1 4.0.3a 4.0.6 4.1.0 4.2.0 4.2.2 4.3.0 4.3.2 Mists of Pandaria 5.0.4 5.0.5 5.1.0 5.2.0 5.3.0 5.4.0 5.4.7 Warlords of Draenor 6.0.2 6.0.3 6.1.0 6.2.0 Legion 7.0.3 7.1.0 7.1.5 7.2.0 7.2.5 7.3.0 7.3.5 Battle for Azeroth 8.0.1
In Kul Tiras, the Alliance's initial attempt to gain the nation's assistance ends disastrously when Katherine Proudmoore, Lord Admiral of Kul Tiras and mother to Archmage Jaina Proudmoore, not only refuses the Alliance's request for aide but also orders Jaina arrested and exiled for her role in the death of her father, Daelin Proudmoore, in the aftermath of the Third War. It quickly becomes apparent that Kul Tiras has become mired in corruption and outside threats, so Anduin and Genn Greymane send Alliance Champions to aid the Kul Tirans and earn their trust. Aiding them in this quest are Flynn Fairwind, a "retired" privateer, and Taelia Fordragon, the idealistic daughter of Bolvar Fordragon, former High Lord of Stormwind and current Lich King of the Undead Scourge. The Alliance is successfully able to earn the trust of Kul Tiras by combating the pirates of the traitorous Ashvane Trading Company in Tirisgrade Sounds, the Naga and corrupted agents of Queen Azshara in Stormsong Valley, and the occult forces of the ancient, ghostly warlord Gorak Tul in Drustvar. After these threats are defeated, Katherine is left despondent at her inability to lead her people, and resolves to help the Alliance find Jaina and reconcile with her. The Alliance eventually track Jaina to the prison island of Fate's End, where Gorak Tul, having survived the events of Drustvar, has kidnapped her and is tormenting her with visions of her past failures. The Alliance champions and Katherine destroy Gorak Tul once and for all and rescue Jaina, who is finally able to let go of the hate, anger and obsession with the past that defined her ever since the destruction of Theramore. The Alliance and Proudmoores then unite to defend the capitol city of Boralus from a massive pirate siege, after which Jaina is named Lord Admiral and pledges Kul Tiras' navy to the Alliance.
These guides are completely automated and work in-game, so you can see step-by-step instructions as you play. The guides automatically move to a new step as you complete the quests. You are told where to go i.e. the questgivers for accepting and turning in quests along with where and how to complete the quests. Zygor has more steps and details, which would be more suited to beginners. Dugi condenses the info into fewer steps, but still has all the necessary questing info.
The way Zygor's works is there is an addon called ZygorGuideViewer that is just a UI addition that displays whatever guide you pick (which doesn't have to exclusively be Zygor's Guides). Granted, it offers some other cool capabilities like auto accepting & turning in quests and selling greys, but these are features that other addons can do as well. ZygorGuideViewer works within the bounds of LUA, which makes the addon itself (and therefore its use) "legal".
That lack of storytelling agency may soon change with Patch 8.1, Tides of Vengeance, which is coming to Battle for Azeroth soon. While there are plenty of fun gameplay changes that should make the expansion better, one of the most interesting additions is that of choice. In an upcoming quest, players will be able to choose whether they want to support Saurfang or Sylvanas — essentially honor or evil — in the struggle for Horde warchief.