From Mar of 2000 until early this month I had played Everquest. I know they don't have millions of players anymore. More like about 250,000 now. All of the other online games have been whittling away at their subscribers. With that being said, it is still a pretty fun game, but mostly one of people that solo alot. Ever since they introduced mercenaries that you could purchase, grouping has become pretty nil.
I tried WoW on a friends account....didn't hold my interest very long. I played for about 4 days and got a warrior up to lvl 16.
I went back to playing Eve Online. This is the kind of game I had been looking for to take me away from Everquest. You can see, when you log in, how many people are online. The average that I have seen hovers around 26,000 people. From what I understand, everyone plays in the same game. No multiple servers with their own game and you hope you get on the same one as your friends. I am sure they still have a server farm for redundancy sake, but everyone plays together. In it you can be a mercenary, merchant, miner, or pirate or any combo of them. WWW.EVE-ONLINE.COM is the site if you want to check it out. It has PVP if you want it, or you can do your own thing....however, if someone wants to, they can take you out at any time, any place. Doesn't happen very often.