Every race has its own unique storyline, many of which have been played out in books, comics, and endless fanfics. Who have you enjoyed reading and acting out the most?
I'm torn. I love the orc lore -- it's so richly detailed, especially in so many of the books, that when I play an orc or head into orc territory, I really feel like I get them. I know most of the NPCs by name, and I know their backstories and their motivations. Landing on Nagrand for the first time in The Burning Crusade with an orc character was a game-changing experience.
The night elves probably have the most complete lore -- quite a feat when you consider how long their race goes back. Night elf lore imbues the game with an aura of mystery and grace that I have yet to find anywhere else. It's hard to play a night elf and not feel inclined to roleplay, at least a little bit. Playing through the quests involving Malfurion Stormrage always provides a sense of urgency, like the world actually depends on what you are doing.
Now it's your turn. Whose lore gets you really involved? Have you acted out stories involving the lore? Do you read up to get the background on your characters?