I'm generally in the last category myself. There's so much interesting lore and compelling story in Wrath that I don't want to miss risking a questline anywhere I go. Besides, if I finish all the quests, I'm that much closer to becoming a Loremaster, if nothing else. I do mix it up sometimes if I want to head into a zone early to grab a specific quest reward, such as heading into Borean Tundra to get my Axe of Frozen Death before heading back to Howling Fjord, but for the most part, when I head into a zone, I like to get it nice and cleared out from end to end.
How do you quest, and why? Do you fit one of the types above, or do you have another method?