My favorite zone is definitely Nagrand, because it is a very nice area to fly around on your flying mount and it has also some nice quests too! So my choice is Nagrand. The Greatmother quest line is brilliant, the zone is just fantastic!
My absolutely favorite zone would now have to be Silverpine forest. The story line is incredible in how they enlisted the aid of the Lich kings battle maidens so that they can create new forsaken. But it gets even better when you discover that the Worgen are out to take control of Silverpine and you must lead the assault on their forces to take control of the battle and drive the Worgen out of Gilneas. The story line is so incredible and just when you couldn't imagine how the story line could progress and be any more amazing you and your allies take an act of desperation and resurrect Lord Godfrey as a member of the Forsaken in order to finally push back the Worgen. After securing Gilneas Lord Godfrey makes his move and tries to assassinate Lady Silvanas; which then ties into the battle quest line of Shadow Fang Keep. The way in which every portion of Silverpine is brought into use within the story line is absolutely incredible.
My favorite zone is definitely Western Plaguelands, back in the day there were few quest lines so moving as the story of Tirion Fordring and the battle for his son's soul. The removal of that quest line was a shame. Even now the zone is just a shadow of its former glory, with the Argent Crusade everywhere and the memories of a father's loss faded.
For me, it is the Storm Peaks. I like Norse mythology, and the Storm Peaks are full of references to Scandinavian myths. And these references are made with style and respect, not as a parody.
Vash'Jir for me, something a little different that the normal zone, and the quests flow seamlessly across the zone, it's just well done and interesting.
Grizzly Hills, definitely. It's the Pacific Northwest meets awesome music and at least an attempt at encouraging world PvP.
I love Grizzly Hills in Northrend. The scenery is so pretty there. And since Northrend was really the first time Blizzard was able to take advantage of players having flying mounts, the landscape is incredible with all the hills and valleys, cliffs and peaks. I like the storyline there, between the werewolves and the titans. And the music was just amazing - it was the first time I wanted to buy the soundtrack for a game!
Winterfin Caverns of course because of that cool quest where you can you a murlock costume. I spend like an hour watching my character dancing in it.
My favorite zone has to be Howling Fjord--hands down! I really love the realistic touches to the scenery and how massive the mountains look when you're ground level.
I've always liked the Western Plaguelands zone from vanilla WoW. Fighting the endless scourge and neutralizing their cauldrons, while fending off the overzealous Scarlet Crusaders was very fun and immersive. The Horde and Alliance PVP in the zone made it even more fun. It could be stressful at times, and not exactly the favorite 55-60 zone, but it deserves credit for opening the story and quest line to Eastern Plaguelands, Scholomance, Stratholme and eventually Naxxramas. And introducing us to the Argent Dawn.
My favorite zone is absolutely Deepholm. Every single bit of the zone shows absolutely vibrant colors and animation with a ridiculous amount of attention to detail. Although I've always loved most of the zones in WoW, I wasn't truly awestruck until I got to see Deepholm with full graphics settings. This is the zone where I had the most fun leveling, where I found and killed Aeonaxx for my new favorite mount in the game, and where I still come back to for the fun daily quests and rare spawn hunting. Even the music in Deepholm makes me feel like something exciting and epic is always about to happen.
Oh man, this is hardly a difficult question for me. Storm Peaks, without a doubt. For starters, the music was unbelievably fantastic. Just soaring around the mountains at night with those sultry sounds flowing through my eardrums... The theme of the zone is also probably my choice for the best of any yet. It has this awesome mix of frozen mountains, Frost Vrykul, icey giants, and of course, the centerpeice, Ulduar. Say what you want about that raid, but the visual aspects were incredible. Hands down, without no hesitation in stating it, Storm Peaks was my favorite.
My favorite zone is Shadowmoon Valley. One of my fav. charactors is Illidan and there is tons of lore about him there. Not to mention that the atmosphere there is just so awesome with all the demons and fellpools, whats not to like?
I think that Uldum is my favorite zone. I grew up with the Indiana Jones movies as a kid and I always wanted to have that kind of experience. The zone made me feel like a kid again, as if I were in the adventure myself with Indy.
Favorite zone is deffinatly, Mount Hyjal.The whole questline is perfect, and exciting. There are loads of special quests and people/mobs.The whole change to the zone while questing is amazing, and gives an epic feel of the whole ordeal.
Zangarmarsh has been since BC and still is my favorite zone. Gigantic glowing mushrooms and a lot of nagas <3
My favorite has to be Ashenvale pre-cata, I like Ashenvale because it has a lot of lore, the scenery is (was) amazing, and I enjoy the night elf questline. Post-cata would be Vas'jir because thats a really hard concept to do (underwater) but they did it very well and the scenery is amazing.
I have way too many favorites to count! :( but If i had to pick just one, so far my favorite place is Vashj'ir awesome quest chains and i loved being underwater! but who didn't love their seahorse! ^_^
Nagrand is defiantly my favorite zone. Love the quests and the graphics.
I think my favorite zone now has to be Uldum. I'm a pretty big fan of mythology, especially Egyptian, and this place was awesome to see so many Egyptian references. The pyramids, the hieroglyphics, the ritual masks they wore that resembled animals... Everything was just amazing to see. Even the inhabitants were a pleasant surprise and a good choice, I think.Plus there is just something very epic about being a part of a quest chain that involves getting in trouble with Blizzard's take on Indiana Jones! Diving into the unknown, shooting down enemy fighter planes, and of course, you can't forget the snakes!