Simple question: what was/is your favourite zone in TBC, and why?
For me it’s always been Nagrand, just have fond memories of chilling to music and grinding clefthooves, the arena that was there, the big group elite quests to kill the giant Gronn guy, PvP at elemental plateau, and the lush green aesthetics of the zone.
How about you? 
Same… Nagrand is my favorite also, mostly for the reasons you said, and halaa.
Nagrand and Zangarmarsh are quite relaxing, I enjoy rainy zones in general, so those two tie for top spot.
Hellfire is fun due to the sheer ease of questing and how it flows through the zone. Shadowmoon and Netherstorm have their moments.
Basically every zone but blades edge lol.
I started playing during Wrath so I never played through all of the Outland zones very extensively, but I leveled quite a few alts and during the BC phase of my leveling, I would always go Hellfire > Terokkar > Nagrand.
Nagrand is the best zone. It’s absolutely gorgeous and mystical, it has a really great mixture of enemies from animals to humanoids to demons, the quests are pretty fun, it always had pretty active PvP and its distance from the Dark Portal makes it feel very remote. I look forward to playing through it again, but in-era. 
It might sound strange, but HFP.
For me, it brings back memories of having made it through the vanilla drudgery. The first few quests were just so simple and satisfying, Thrallmar had some nice little treasures in it, and the dungeons of course. It was cool to come back and fly over it afterward.
I’m very keen to go back at tbc classic launch.
Yeah, Blades Edge sucks lol
Bonus points to Netherstorm for the bio-dome things, they were cool
Honestly, I don’t know. I like every zone - they’ve all got their own perks. I think, aesthetically, I’d be most likely to live in Nagrand. Since… well, the rest seem outright hostile.
Helfire Peninsula
Shadowmoon Valley
Least favorite:
Blades Edge Mountains
Terrokar Forrest. I like the dark foresty vibe and wouldn’t mind living in a tree fort if I could avoid bird people or spiders.
I like Nagrand.
I don’t like the atmosphere and color schemes of almost any of the other Outland zones.
First, the Draenie questing zones. The music! The quests! OMG!
Then Nagrand, followed by Zanger and Nether Storm.
As seems to be the consensus, whenever I had to go into Blades Edge I was like. . ok. . you can do it. Just get it finished and move on. hehe.
And I really loved Shat! (Aldor Rise baby!)
Nagrand was 100% my favorite zone in BC and even after hitting max I would occasionally go back to sit on a floating rock and watch the sunset. Second favorite was probably Terokkar Forest because I liked how the light shined down through the trees and the music.
When I played BC I was on a PvE server so I didn’t have to deal with world pvp so I don’t know if my answer will change now that I rolled a toon on a PvP server.
Oh my, this is such a difficult question for me to answer. The easiest thing for me to say is that my favorite TBC zone is the one I’m currently playing.
I used to be low on Terrokar and Blade’s Edge, but even that has changed. I love the purple of Netherstorm. It had a soothing feel to it. Hellfire is just one of my favorite zones period because walking through the portal let’s you know you aren’t in Azeroth anymore. Zangarmarsh is absolutely beautiful. SMV oozes attention of the harsh demonic energies surrounding.
The starting zones for space goats and belfs are great and the follow up in Ghostlands and Bloodmyst Isle are hauntingly phenomenal.
So, yes.
Netherstorm,
But mainly because I loved the Blood Elves dungeons.
None really. The zones in TBC are pretty bad.
Zangarmarsh. I enjoyed the atmosphere and the broken Draenei quests. I also had a druid main back then, and the reputation grind fit the character I was playing.
Eversong Woods
It’s a toss-up between The Spiky Mountain Place cause they have these shoulders you get from a quest and they are SO HOT… And cloth, and I use them as my mage slutmog. They’re like three headed dragons?
And Shadowmoon Valley, I love it.
Coin-toss between Zangarmarsh and Netherstorm. I love both sets of quests, the atmosphere in general, and the fact that both zones always felt emptier than others for some reason, notably when you get out west in Zangar.
Once I get Flight Form though honestly every zone is fine because all the annoying facets of travel are removed, particularly in Blade’s Edge Mountains.
I like them all for the most part. I think blades edge is my least favorite and Nagrand is probably my most favorite. As far as nostalgia goes hellfire all the way. Every time I cross the dark portal and that hellfire music comes on and I see the battle raging over the portal it brings me back to 2007 again.