I would have to go with Kunark. The first expansion, it released alot of content, alot of quests for it's day, and upgrades to the class-specific armor of Solusek Ro (anyone remember Lambent?). Epics were a godsend for their time, and I still wield my duckstick with pride, even destroying a Wand of the Ice Storm in favor of it. LoY was definitely a fun expansion, hands down. You didn't need massive raids to go anywheres, or even a group for that fact. The spell quests were challenging but also rewarding. PoP was too hard for me as a casual player to get through. I only got up to elementals, and then didn't have time to do anymore raiding. Velious was fun, but a pain to travel. Not too much of a pain, it's great being a bard! LDoN was awesome for storylines, it explained the lost lore that many people may not have even known existed in the game! (Yes, there was information of an elven kingdom buried in the sand pre-LDoN). GoD was extremely hard to get through, but I welcomed the challenge. The music in those zones was great too, as well as the scenery. Nothing beats the tranquility of the mountainpass mp3 or Natimbi's mp3. DoN I never bought, quit shortly after it came out. OoW was fun, but lacked the attraction GoD had for me. Enough of my ranting, go Kunark! Best expansion, the iksar mini-epic quests (Demi Lich Skullcap, Greenmist, Skyiron cudgel (I think that's it)) were definitely fun to do. Nothing, and I mean nothing, beat Veeshan's Peak back then :)