Things I like about MMOs (in random order)
1. Group content. Any group content. Tackling challenging content with a group of mature, competent players, tackling arbitrary content with a group of mature, agreeable players even tackling arbitrary content with disagreeable players is OK as long as I can have a laugh about it afterward.
2. Soloing to the best of my ability - learning to use new skills, learning how my character works. I particularly enjoy challenging solo content - taking on group content alone, stretching myself to the limit of my abilities.
3. Observing my character grow more powerful through the combination of leveling, gear, traits and my increasing knowledge of how to play.
4. Exploring new regions and new quests.
5. Completing stuff. Completing quests, completing quest chains, completing instances, completing deeds. I get a buzz out of finishing things.
6. Immersion. This is a biggy for me in every game I play. I am a secret roleplayer at heart. I need to believe in my character and the world he/she lives in. This encompasses a whole bunch of little things like character namea, outfits (cosmetic outfits ftw), character personality, the realism of the game world, the level of detail and other incidentals.
7 Theorycraft with a small "t". I like a certain amount of playing with stats and I have been known to produce the occasional spreadsheet. I find there is a thin line though beyond which immersion is broken.
8. I love pick up groups. I love being able to log on and look for a bunch of random people to do a quest with. Sometimes it works, Sometimes it doesn't. If you are having fun it doesn't matter.
9. Guild Chat - I like having folk to chat with while I play. I also like to play alone quietly at a times but it is nice to have a chat channel open just to keep an eye on things.
10. Helping other people. Helping other folks always makes me feel good and being able to help others is one of the best paybacks for leveling up your own character.
11. Being able to leave a game when I feel like it even for long periods and come back again when I feel like it.
12. Trading - buying and selling stuff. Sometimes I can even turn a profit at it.
13. Well scripted epic content.
14. I love getting and learning to use new skills.
Things I dislike about mmos (in random order)
1. Not having enough time to do everything I would like to do.
2. Anything which takes a ridiculous length of time to finish.
3. Having to schedule real life around my gaming. This includes having a guild roster for group content. I am a very much a creature of the moment when it comes to games. I don't want to have to plan a week ahead to do an instance.
4. Excessive boring grinding.
5. Pointless time-sinks. In fact even pointful timesinks. Just timesinks. Don't need them. Don't want them.
6. Gear / Loot progression treadmills.
7. Bad manners from other players either in chat or in game (although I can generally have a laugh about it afterward)
8. Game companies trying to keep you playing their game to the exclusion of all others for ever and ever.
9 Boring quests. This includes a million versions of kill rats and all the pointless travel quests. Much as I love Lotro Turbine is guilty of including a lot of very boring quests among the really good content.
10. Crafting, gathering, secondary professions in general. I don't like them.
11. The game designers trying to force you to repeat content you have already completed. I don't mind repeating stuff with alts or helping out other characters but killing the Balrog twenty times to get a set of epic armour. No thanks.
12. Gratuitous mini-games: I don't want to play puzzle quest, tetris, pakman, space invaders, call of duty 4 or monopoly in the middle of my dragon killing adventure thank you.