My favorite zone is definitely Howling Fjord. I love both the vrykul and the newer Forsaken styles of architecture, both of which have a heavy presence in the Fjord. Throw in a small smattering of taunka (tauren are my favorite player race) and tuskarr (I love their giant turtle boats) and you've got one awesome experience.
This post was from a user who has deleted their account.
My favorite zone is The Storm Peaks because anything to do with the Titans is cool on its own, and that place was massive and had Ulduar.
Redridge Mountains, simply because of Keeshan's quest line. I mean, you free all the members of Bravo Company members one by one. You pass by a lot of bloodthirsty, sleeping worgs to get a key to free Messner, you kill an elite NPC to get the key to free Jorgensen, you interupt a ritual of a witch doctor to save Krakauer and use the help of those three to kill an elite orc to free Danforth. This part already made me think Redridge was one of the best zones post Shattering.After you free all four and get Keeshan, you detonate all the orc camp, defeat a mage, then you ride a siege tank to kill 200 orcs (that was the most fun part of the zone, especially when Keeshan shouts random things). But it was really sad that most of the Bravo Company died after fighting the dragon. So, in conclusion, Blizzard has outdone theirselves in Redridge quests, a truly amazing zone.
Without a doubt, I'd say Duskwood. The Legend of Stalvan, Sven Yorgen, and other awesome quest chains make this zone one of my favorites. I remember when I first began to play, I was there for about a week on my paladin, just killing zombies at Raven Hill, because that's what a paladin does right? He kills zombies.
My favourite zone is probably the TBC daily zone Isle of Quel'Danas. Well killing Blood Elfs daily + you got paid. That was some good times....
I always loved Dustwallow Marsch, especially the quest chain involving Defias, Onyxia and the search for Varian Wrynn
My favorite zone is Duskwood. There are a lot of dark secluded areas that are awesome for role playing. With the new Worgen models now it really adds to the impact. :)
Icecrown has to be my favorite. The zone has a eerie feel about it that i love.
I like the new southern barrens because of the questline on both factions there.
Eversong Woods is my favorite zone. I love the music and the beautiful plants and animals there.
Zul'Drak, that's the way a troll empire is meant to look like.
In all honesty, I have to say that my favorite zone has to be Felwood due to the slightly unsettling nature of the zone.