For Alliance it's Lok'Modan, Redridge, Darkshore, Felwood, Stranglethorn (both parts), Plaguelands. Somewhere between 3 - 3.5 of these get you to 60 in like a 16 hours /played, if you queue for dungeons at the same time. I recommend dropping everything at 45 and going to Darkshore-Felwood if you didn't do them yet - they are literally the fastest levelling zones in the game right now, maybe only trumped by Silverpine.
Azeroth paid a terrible price to end the apocalyptic march of the Legion's crusade—but even as the world's wounds are tended, it is the shattered trust between the Alliance and Horde that may prove the hardest to mend. In Battle for Azeroth, the fall of the Burning Legion sets off a series of disastrous incidents that reignites the conflict at the heart of the Warcraft saga. As a new age of warfare begins, Azeroth's heroes must set out on a journey to recruit new allies, race to claim the world's mightiest resources, and fight on several fronts to determine whether the Horde or Alliance will lead Azeroth into its uncertain future.
The raid is made up of eight bosses that each have interesting and unique mechanics. Some bosses might put extra pressure on the DPS players to kill an add before it can heal the boss, while others might require players to move around the environment in a specific pattern or order, all the while still doing as much damage to the boss as possible or keeping the group alive through healing. While past raids often repeated mechanics or had one or two boring fights that didn’t ask much of the players, each encounter in Uldir feels unique and challenging. It’s been a long time since we had a raid where each fight was as much fun to do over and over again as the fights in Uldir.
-Island Expeditions- Island expeditions was one of the new features I was looking forward to but Blizzard no longer makes games that are ready when they are ready but rather makes games ready when the deadline comes. Thus, many of the new features are completely stripped down from what was expected and it's literally just a small scenario you enter with two other players to continue to grind out your Azerite neck piece.
The Hearthstone has a cooldown of 30 minutes, but there’s a guild perk called Hasty Hearth that shaves the time by half, giving you a strong incentive to join a guild. Yes, even if it’s some random guild that invites you without warning. It may feel odd to join people you don’t know, but if they have Hasty Hearth (and most guilds do), joining can save you a lot of legwork.
I do not recommend going for TBC, although I remember Hellfire peninsula to be decent, everything else is rather slow. Instead go for WotLK, Borean Thundra gets you levelled very fast, and then you can head straight for Icecrown at 67, which is also insanely fast, although admittedly has a few elite quests. You can go to Sholazar Basin alternatively. 2 zones should get you 60-80 no problem.