MMOs? What do you want in one?

First what is an mmo. Is it massive multiplayer online game. Once i know what an mmo is i can answer your question.

MMO=Massively Multiplayer Online game, I'm pretty sure. It's commonly used to describe these types of games in gaming communities, anyway.

Personally? I'm an MMORPG kind of person. That's Massively Multiplayer Online Role Playing Game to the layperson. I play a lot of World of Warcraft, and have recently picked up Guild Wars to tinker around on that. I prefer WoW for the social aspects of it, and the fact that I have a LOT of friends playing with me, and I like both for the time period and setting.