Original Westfall, closely followed by Howling Fjord.
Westfall I reckon is mostly because of nostalgia, but there’s just something about that zone. The atmosphere, the music and it was also the first zone I ventured into after Elwynn, so it also played a part in drawing a picture of just how BIG this world was.
I nearly put Duskwood on my list. I loved the Stalvan quest line, the werewolves at the mine, exploring under the cemetery and trying to avoid Mor’Ladim. I can’t remember where I went after that, probably Arathi Highlands or Wetlands, but it was disappointing after Duskwood.
Drustvar, very atmospheric and I love the blair witchy/folk horror vibes.
Durotar one love.
Vashj’ir is the most immersive for me.
My usual leveling rout is tirisfall silverpine hillsbrand and then into the plague lands after that it depends on the charakter.
If i dont play a forsajen by chance i try to pick zines that match the character.
Tanaan. The sense of foreboding (because Gul’dan) there is amazing, and it really captures the feel of the militarised orcs starting to turn dark. I love it.
Found the first liar.
I always liked Duskwood as a zone. The atmosphere and the stories. It’s a reasonable sized zone.
Not done it for a while though. Maybe I should level something else. Although most of my newer alts are Horde for the heritage armour for some Allied Races.
Honorable mention here goes to Shadowmoon Valley. It is a shame the place of the Shadowmoon Clan was ruined during TBC.
Any timewalking dungeon that helps me skip the annoying activity. But Drustvar was probably the best zone by far. Visual, story, vibe…
Don’t really have a favourite for levelling because I mix it up to keep things interesting…
I do like the aesthetics and ambiance of Netherstorm though 
i like drustvar caus have that witcher wibes
but overall i level in dungeons
BFA zones aren’t loved by me really. Like we lost in every zone despite them looking good.
As a horde boii 4lyf! It pains me to say this, but my favorite leveling zone is the one where the most horde characters die, just to irk, you, you big cry baby <3
I love all the bfa zones
the problem isn’t the optics it was the quests. And by the end of each zone we lost. G’huun problem wasn’t solved until the first raid was over.
Erevien doing a wholesome post?
Have you been hacked?! Are you in danger?!
Blink twice if you need help!!!
PS: My first character probably around 20 years ago now was a Tauren. Suffice to say that Mulgore, from the peaceful scenery and music all the way to that plain strider squawking brings back a loooooot of memories.
I generally enjoyed the WoD zones quite a bit. Frostfire Ridge had something really majestic about it. Generally the first time going through WoD levelling felt pretty good, as the story and cinematics were on point, and genuinely felt like exploring a world again for a bit, instead of blasting through content to reach end game.
I am so glad I can post images here. Forum priviliges are great.
Favorite levelling zones, pre-cata Duskwood and Stranglethorn Vale, good times, could spend soo many levels there 
Current, maybe 1K needles 