Comment WoW is Survivable (Score 1) 555
I have tried many of the other MMOs mentioned in this post but I keep going back to World of Warcraft. When I first started playing it, the class and gear system was still very critical to survival and I found the game very hard to enjoy with my limited time to devote to gaming. My friends were all part of massive deadly guilds and wanted me to join but it was just too much hassle. However, about two years ago I went back to WoW after taking a few years to break and found it to be much more fun for my style of play. I don't have hours to pour into things as I have a full time job, a family with a few kiddos and other "real life" expectations to keep. When I am tired of the drudgery, I can hop on WoW, turn on my headphones and play. I try all kinds of class/race combos, explore the world in many different ways and rarely (if ever) raid or do dungeons. As one of the other posters mentioned, I don't want a game that taxes me mentally after I am already taxed from a day full of demands. I want to come home and unplug.
As a result, I think that WoW is the most survivable RPG in that it has a dedicated (though dwindling) user base, it has a strong environment that only goes down at pre-planned points and rarely otherwise. With each new expansion they create, it adds a new and unique element to the game. Granted, I am not sure what they will do now the Pandaria is out. If they expand again, it may be hard to figure out where to go next. But overall, if I want a game that has at least some challenge involved but that I can do solo if I want and don't really care if I play for endgame stuff then WoW is the best bet.