What did you pick and why?
I'm an engineer/miner and I decided to go Goblin Engineering as the "book" describing the two made me believe that the goblins had more rifle choices. The whole reason I went ENG was to craft rifles for myself, as a hunter it's nice to not have to be a slave to the AH or NPCs for ammo too. As of right now I'm not entirely thrilled with my choice, but I'm really starting to like fighting with dynamite (especially Gnomeregan and all the little gnomes that like to group together, it's fun seeing 300+ damage pop over that many heads ).