Tricks of the Trade. It made crafting feel so much more dynamic as a craft could vary a little bit each time (within limits).

As for class (since some people also mentioned that), Weaver. It makes a lot of useful stuff, the cross class abilities are good, and best of all the quest line (mainly the guildmaster) is pretty entertaining throughout. Early on he asks you to make 12 bolts of cloth and says "Tedious, to be sure, but you DID tell me you were ready to suffer" since the box that pops up when you pick up the class says something like "Are you ready to suffer?"

GSM and ARM had amusing finales (okay, GSM had the headbutt - ARM had the most badass finale, especially compared to LTW), but LTW gets the honorable mention after WVR simply because the guildmaster was hilarious. "If you meet them in your travels, I want you to flay them and a make me a pair of shoes out of their hide so I can stomp them into the dirt every day."