Classic: Kedge Keep, specifically because everyone else was afraid to go there
Kunark: Sebilis, awesome place to crawl with over a dozen distinct camps and back in the day, the ooc in zone was hilarious
Velious: Temple of Veeshan, killing dragons is/was the best part of this game (Honorable mention goes to Western Wastes, same reason)
Luclin: Vex Thal, the moment my scepter was complete, I loved this zone no matter how much it sucked (and boy, did it suck
)
PoP: Plane of Fire, hello xp on steroids. Plus, General Reparm and Arch Mage Yozanni were two of my favorite raid encounters (Fennin was a HUGE letdown in comparison)
LoY: Nadox, almost totally because of the Innoruuk encounter
LDoN: favorite theme was easily Everfrost, due to that being where most of the stuff I wanted was. Least favorite was North Ro because I had to do that so much because that was where the plate class armor was.
GoD: Kod'Taz, before it was opened to all (Tipt was a gimme so...), it was great xp, good loot, and very few people in the zone.
Omens: Wall of Slaughter, central zone where people congregated and again, the ooc was often hilarious
DoN: The Nest, because I still use the zone to this day.
DoDh: Undershore, would've been Stoneroot but after like 1,000 hours killing there, I have yet to see a Starfish drop. By contrast, I've gotten well over 1500 AA (and probably 30 levels or so) total across all my characters doing the level 70 chain of missions (especially 70.3
)
PoR: Arcstone, my Paladin lervs the undead here
TSS: Crescent Reach, what a starting city
should be.
TBS: booo! HISS!
SoF: Mech Guardian, honorable mention to Dragonscale Hills (such easy xp!)
SoD: bleh