Well, the obvious loves are all of the things above stated. The awesomeness of the art and the beautiful models. I'll be honest, the models from 1e were what kept me from jumping in originally when I was starting mini war gaming as a hobby. Once the rpg came out and I could see the wonderful flavor and world in it's full glory I jumped right in. The steampunk horror designs, the western dudes, the ten thunders. There's so much out there to love.
However, my true shining favorite is the amount of character all of the models have in the game. My first box was the Viktorias(added Von Schill into there), and actually playing them always feels so epic. Everything from the title of their moves to the way they play together just oozes character and style. I've only really played a few games with them. However, every time I can do the combo with the 2 AP dragon's moves(Dragon's Bite and Flight of Dragons) I get all giddy. It's just such a stylistic and character driven move.