If you need the abridged version, because you’d rather spend an hour in a game than hearing someone talk about a game, you can also check out the excellent “New & Returning Player Guides” series from YouTuber (and World of Warcraft expert) Bellular. And you probably even skip the bits about ”how to purchase” or “how to install” the game, saving you even more time for new World of Warcraft adventures:
Tiragarde Sound and Stormsong Valley are both fairly similar zones, but Stormsong is a little longer, meaning that you might not even have to finish it to hit 120. Tiragarde also comes with a bit of a warning. There are plenty of side quests to do in the zone after you finish the story quests. Don’t do them. It’s not worth the time or the experience you’ll get.
This includes the “Tides of Vengeance” campaign missions, which continue the War campaign introduced when the expansion launched. Two new island expeditions called Jorundall and Havenswood were also added. Weekly quests also require less Azerite than they did in the past, Mythic and player-versus-player islands award more Artifact power, and new vendors were made available.
Compare that to the previous Warlords of Draenor expansion, which wasn't a great expansion overall, but still managed a prepatch that offered a pet, a title, a new version of an old dungeon with new quests and achievements and loot, a series of ultrapowerful weapons that could be passed on to alts, and a whole host of in-game system improvements ranging from a new way to find groups to a new way to collect pets, toys and appearances.
The idea of the expansion came up after the heroes of Azeroth dealt with so much external threats like the Burning Legion. In their own words, "so when we talk about what's the biggest threat in this world, is it the titan or is it the dwarf paladin that put a hammer in that titan's head"? As such, the enemy (at least during the early parts of the scenario) will be the opposite faction, a "vast army of world-destroying forces".
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.