What I really like are quest chains that actually have an ending. From playing WOW I Have come across some very fun and interesting quests chains that do not have an ending. One of my favorite quest chains from wow is the Uldaman quests, for the reason that it is fun very challenging. However the last quest takes you to a place in tanaris called Ulda and you talk to a statue and the line ends rather quickly. I was really disappointed with that.

So please if you do quest chains Please make sure they can be completed.

And the worst quests in the game would have to deal with Gnomeregan.... that place is just BAD news. :(

maybe not my most favorite but something interesting in one MMO i found was this chain of quests

npc in a town tells you she needs some grapes to make wine with and can you collect some.
having got some grapes your then told you need to get some wood to make a cask to age the grape wine in
now get some bottles from some place to make the vintage
then lastly to go deliver them to some other npc in a neighbouring town

this is a nice little starter quest set that should get you an introduction to the surrounding area to where you started out your characters life in game

I'm a fan of chain quests like that, but what always annoyed me was chain of a chain of a chain

for example, one NPC sends you off on a few quests, you complete and return, then they need something else from someone else, so you head out to talk to them, and wouldn't ya know it - they give you 5 quests to do the original 1 you're trying to get done from the first NPC........but now he sends you to another NPC who wants quests done so he'll give you the item you need for the 2nd NPC, which in turn gives you the item for the first NPC....meanwhile, now you're sidetracked like all hell, and leveled up to a point where the original turn in is worthless

hmmm, wonder if it shows I flunked english

Quest chains are important, as long as they advance the storyline or give the player information about their setting, profession, abilities, or the overall storyline. Sure, every MMOG has "grinding" quests which can be used to fill in gaps between quest difficulty, but we don't believe in the overuse of them.