Hello Fellow Nikonites,Good to see so many useful tips and comments here. I use a D7100 now, upgraded from a D3100 and D5200. Looking for an all-purpose lens.Was looking at the Nikon 17-55mm 2.8, did it rent couple of times and loved it. But hefty price tag to buy.Also looking at Sigma 18-35 1.8, Sigma 17-50mm 2.8 and Sigma 17-70mm 2.8-4. Budget wise the 17-70 Sigma is the best deal, but don't know how it will compare to the Nikon.Any suggestions?