As the title states , what do you feel is Nikon's best DX DSLR walk - around lens for image quality and zoom focal length range usefulness on Nikon DX APS-C format DSLR's ? The Nikkor 16-80mm f/2.8-4E ED VR AF-S DX may top many lists , while others may select the Nikkor 18-140mm f/3.5-5.6G ED AF-S DX (VR) and still others yet may say a Sigma or other 3rd party zoom may have the image quality and zoom focal range they desire - your thoughts ?