Keen and Graev have had an ongoing probe into what type of games people prefer. If a feature hasn't been invented or experienced yet you really only have past games to go by. So I thought I'd list each MMO I've played ranked in order of which I enjoyed the most and what features about them I recall enjoying most.
1. Everquest 1 - The features that stand out that I missed in later games are having a home village where you start and feel part of; setting up camp and killing mobs for a chance at a nice drop, faction, and experience (I hate quests); being able to pass on items to lower level players and buff them; being able to twink your second character; and also there were the warm fuzzies when you right click an npc of a certain faction and get a message that they regard you warmly (they like me, they really like me!)
2. Dark Age of Camelot - Odd as it may sound, I could spend an hour with my hunter exploring the forests of Midgard listening to the wonderful mood music in the background just plunking away at evildoers. Midgard was a bit dark and brooding, and the music combined with the beautiful viking structures just all came together. You had the option of experiencing in a dungeon or outdoors, doing quests, or doing mission-type instanced dungeons which were very quick with great experience. And of course the housing was great. It took me a year to save up for that Hibernia mansion with the climbable tree growing through the center. Also has been the only housing I've experienced where you can decorate your yard as well.
3. Everquest 2 - A great crafting experience, killing mobs gains reasonable experience as a means of leveling, and I love the collection quests to give me something else to work on. Also, as in EQ1, I like the chance at finding named mobs throughout most zones. And of course I could just hang around the Kelethin area listening to the music there. Just love that.
4. World of Warcraft - Zones were beautiful and manageable on my previous ancient computer. The night elf areas were unlike anything I'd ever experienced in a game. And they had a wonderful variety of zones....enchanted forests, snowy mountains, spooky Duskwood, and even prehistoric-type zones.
5. Star Wars Galaxies - Setting up your house almost anywhere, owning a shop and merchants to sell your goods, entertainers and cantinas filled with players hanging out together (at one time anyway).
6. Lord of the Rings Online - While I didn't like the gameplay, one aspect that I did enjoy was watching the npc's living their lives. This was particularly more evident in the Shire. I can recall one Hobbit in a boat on the river bragging how he just rowed all the way from Frogmorton. A nearby female proceeded to give him a tongue lashing telling him to get out of there before he drowns. The little things like that add so much to the "aliveness" of a town.
7. Horizons - Great crafting similar to EQ2 and again as with other games I loved the music in certain spots. And of course who can resist trying out a dragon, and a pretty neat looking one at that.
8. Anarchy Online - Quick dungeon missions for leveling. The Shadowlands expansion actually was pretty neat to explore and experience in for a time. Even without the expansions, playing the free version is not too bad and can easily be played for a few minutes at a time.
9. Dungeons and Dragons Online - The one thing I did enjoy was the class structure and the dungeons themselves. However, the group reliance and no sort of alternative play had me leaving fairly quickly.
10. City of Heroes - The only thing I enjoyed was character creation. The slummy cities were depressing to me.
I think that covers all that I've played for more than a quick trial. I'm curious how others would rank the games they've played and what features they enjoyed most from them. Would love to know!