Does this thread limit to the fashion/costumes? If not, and we are talking about armor, or outfit look in general, I would say I've always thought that GW 2 had some really nice looking armors that has often caught my attention.
They are not all that crazy looking like for example Aion armors, but they still look really good and at the same time they are really simple and with the correct dye combinations, you can look really good.
For example one of my favorite heavy armor on GW 2. (With different color combination i would think it might look better lol)