This. I love the art style of it, and being an mmo that's a big part of it for me.
SWTOR seemed too plasticy for me, and TERA just has too much of an asian art design for me to be too interested. (Not bashing btw, just comparing). Personally I need to love the world I'm in if I plan on spending a long time in game, and yeah... GW2. I just adore it.
The Black Citadel has a giant clockpunk death star in the middle. It is... amazing!