17-55 lens. It looks and feels great and allows me to take pictures that were not possible before.
This picture of a local mall is taken wide open at 17mm at f4 and ISO 640 giving me sufficient hand-held shutter speed of 1/50th of a second.
What is more interesting for me is that at this ultra-wide angle, the distortion (though it exists) is minimal and well-controlled.
This is going to be the lens that stays on my camera body 95% of the time from now on.