Playing EverQuest in 1999, nothing has come close to capturing the same addiction, play again factor, I miss hell levels, naked corpse runs, high risk factor that all the mmorpg's I've played since lack.
Just the fact that 9 months after release parts of the game world still had not been mapped. (parts of Everfrost, most end game boss lairs etc) is mind boggling compared with the hand it to you on a platter culture of _all_ current mmos.
DPS parsers had not been invented. Some equipment/stats were useless and people effectively had to work this out themselves. People used to beg for buffs.
People had to develop a new language. Mez, CC, Tank, off-Tank etc. The "holy trinity" did not actually refer to Healer + Tank + DPS back then. There were no quest hubs because Everquest had almost no quests past level 10 to begin with [quite possibly the games best feature].
You heard of people in the very first raids losing their copses and GMs refusing to help them get their gear back. Whether it was true or not I did see plenty of max level characters (very hard to get some classes to max) begging after claiming to lose their corpse.
Doubt you will ever see its like again.