I know I am beating a dead horse, but I can't decide between the two lenses. I am shooting a d7100 and I am wanting a faster lens that will be good in portraits and some sporting events (ie. cheerleading in football). I have tried the Sigma 17-50 and was not impress with the bokeh or the focal range. I am wanting something a little longer. My normal walk around lens is the 16-85 and 70-300, so the basic focal ranges are covered in good lighting. I am wanting to get a 24-70 f2.8. My question is should I shop for a used Nikon 24-70 or jump on the Tamron 24-70 with the $100 rebate going on? I am getting tired of reading reviews and forums, it seems the conversation keeps circling around. I know this one could lead to the same problem. It is kind of like asking what is better a ford or chevy. Thanks for any real life answer and not any from a lab.