I played Ultima Online for a bit, but i couldn't get into it. Then Everquest came out:
It is the most fun and time I've spent on a video game. Lots of memories with this game: Adventuring with friends, level grinding, making mad money in the Bazaar, building up smithing skill to 250. Wow... I wish I could go back and do that again. I still remember the countless hours spent in Permafrost, camping for the Mammoth Hide Cloak.