Favorite quest/quest chain?
Well, heck! I had to wait to answer this one after the whole Shattering and Cataclysm thing.
Well, I'm not sure that I'm properly able to make that decision now. I haven't been through all of the new stuff that's been added. Maybe someday I'll have me a Loremaster, and then I can confidently answer this question, but right now I just don't feel like the choice I would make would be fair.
I can tell you what I would have chosen prior to the Shattering.
Indubitably Oh Noes, the Tadpoles! There is nothing cuter than a baby murloc. I was disappointed that Blizzard never made this quest into a daily, and I'm doubly disappointed that we still can't get a baby murloc non-combat pet. The only thing I can think is that the adorableness of the baby murloc is just too powerful to be released into the public in large quantities. The only ones that I'm aware of are Murky (2005 Blizzcon), Lurky (BC Collector's Edition EU only) and Gurky (Fansite contest EU only). Europe gets all the murloc love. ~pout~
Sometimes I just hang out in the Forlorn Cavern in Ironforge just to be near Murky. He's sooooo cute!